"It has to be Chromium"

Chrome defaultism, and so websites are usually made for Chrome, often disregarding testing on Firefox completely, and so they work a bit worse here and there

Also no Google connectivity

Huh, I haven’t really noticed any differences since making the switch. What do you mean by google connectivity?
- Chrome browser will let you log in with your Google account which means things like passwords that are saved to your Google account will auto fill
  
  Firefox Sync exists though, and it does the same.
  
  Yup but that doesn't really help people who already have their passwords saved on Google on their browser and phones
  
  I'm a Firefox user and pretty tech savvy and I really didn't know it was possible to port my passwords from Google password manager into Firefox. In any case I use LastPass as my password manager, but the point is this isn't common knowledge for the average person and sounds just like an extra step/hassle. Just trying to be devil's advocate and answer the "why don't people just switch" question.
  
  Speaking of Firefox sync, Firefox has this bug when you're importing your passwords from other browsers, it doesn't sync to your account. Only your manually inputted logins will be synced.
  
  Ohhhh, I didn’t even consider that being a deal breaker for some people, but I’m pretty sure Mozilla will let you transfer all your saved passwords from chrome.
I dragged my feet for a long time before switching from chrome to firefox a year or two ago for that exact reason. When I actually did switch it was practically seamless, I haven't run in to any website that has been problematic on firefox but not on chrome. The only thing i dislike is that i haven't found a way to have a custom newtab-page but still be able to directly input text to the navbar, so i always have to do ctrl+t -> ctrl-a.
- By custom new tab what are you looking for? You can make the new tab display your home page, I think a blank page, and with extensions you can make it do almost anything with a new tab.
  
  I've configured it so that when i open a new tab it will by default open the url to my calendar. It does not select the url in the navigation bar, so if i want to input my own url i first need to select the calendar-url so that my inputs deletes the existing text. I do think that the custom url new-tab is an extension though so that doesn't really help my case (not at the computer so can't check).
What sites have issues with Firefox? I've been using firefox exclusively since 06 besides trying chrome for 2009-2010 and never had any issues. Not saying they don't exist but it seems like a very small amount that won't function at all.
- Anything containing WebGL and anything containing complex CSS/JS animations comes to mind, also Canvas (even though it rarely used, still lags like a motherfucker), Firefox really suffers in that regard, but they recently promised that they will fix it; and I remind you that because of hardware decoder legal ussues Firefox sucked very hard at 4K and 120 Hz YouTube on Linux for a long time too
  There are others, commonly created because Firefox focuses on privacy, and so, for example, all internal website timers can only count by 0.1 seconds because anything less will open you to tracking vunerabilities, often settings sacrifice performance for data safety like this
Also no Google connectivity
I wish people would see this as a feature, not a drawback.

I don't hate it, I really want to like it. It's just that I have a rather niche issue that really bugs me and forces me to chromium (or derivatives).

FIDO2 / YubiKey support on Chromium is far superior compared to FF.

Ah gotcha. I don’t use a lot of 2FA outside of duo.
- Hey, you should. Great way to secure your accounts.
  
  I use bitwarden for most of my password creation and storage. I think they have 2FA so I may look into it.
  
  I'm pretty iffy on 2FA. I'm using it for several things but I don't like that my one and only option for that is this one smartphone. If I drop the phone in a lake, I can't do Google anything anymore, or do some other crucial things. If I decide to step down to a dumb phone, no, I can't. I'm just locked into this permanently, now. Half the internet is off limits if I lose, break, or decide to get rid of my phone.,
  I've gone from having two options for net access - phone and PC - so a primary and a backup, to having one option, both of them at once, and one is none.
  It's a single point of failure that's already vulnerable to SIM swap attacks and even shoulder surfing. You're highly reliant on the target org you're logging into, and whether their setup process is janky.
  2FA makes sense in broad theory, it doesn't make sense in practice, where no options except for your one and only smartphone exist for 2FA. They've not developed some other method and don't appear to be trying. It's just that or fuckin nothing.
  It should be smartphone plus other thing as 2FA options, so the phone can be lost, stolen, destroyed, without leaving you up shit creek, and yet that other thing refuses to show itself.
  
  and yet that other thing refuses to show itself
  You can buy a dedicated 2fa device. You can set your Google account to use the hardware key instead of sms verification. I don't use sms 2fa on any of my accounts. Hardware security keys are inexpensive and work when you lose the phone. Yubikey offers numerous products that do what you want. You can also have 2FA keys on your smartwatch.
  
  I'll have to look into that, thanks.
  
  Yeah, that’s always been my hesitant, and I don’t really have the physical assets, financial assets, or intellectual property that would really demand the need for 2FA on all of my accounts.
You mentioned chromium and not chrome, so I'm assuming it works well in Brave?
- Yes, which is what I use. I don't really like the company and people behind it, and they've did some shady stuff but the other chromium browsers aren't really any better.

A lot of websites will block your access if they detect firefox too

Because it is bad, bloated, bookmarks are horrible, end users have constant problems that aren't even their fault. I literally am using Opera now to avoid Chromium because FF has gotten so bad

Opera is rebranded Chromium