Looking to build my first PC in almost 30 years; What should I be on the look out for?

It looks like !buildapc community isn't super active so I apologize for posting here. Mods, let me know if I should post there instead.

I built my first PC when I was I think 10-11 years old. Built my next PC after that and then sort of moved toward pre-made HP/Dell/etc. My last PC's mobo just gave out and I'm looking to replace the whole thing. I've read over the last few years that prefabs from HP/Dell/etc. have gone to shit and don't really work like they used to. Since I'm looking to expand comfortably, I've been thinking of giving building my own again.

I remember when I was a young lad, that there were two big pain points when putting the rig together: motherboard alignment with the case (I shorted two mobos by having it touch the bare metal of the grounded case; not sure how that happened but it did) and CPU pin alignment so you don't bend any pins when inserting into the socket.

Since it's been several decades since my last build, what are some things I should be aware of? Things I should avoid?

For example, I only recently learned what M.2 SSD are. My desktop has (had) SATA 3.5" drives, only one of which is an SSD.

I'll admit I am a bit overwhelmed by some of my choices. I've spent some time on pcpartpicker and feel very overwhelmed by some of the options. Most of my time is spent in code development (primarily containers and node). I am planning on installing Linux (Ubuntu, most likely) and I am hoping to tinker with some AI models, something I haven't been able to do with my now broken desktop due to it's age. For ML/AI, I know I'll need some sort of GPU, knowing only that NVIDIA cards require closed-source drivers. While I fully support FOSS, I'm not a OSS purist and fully accept that using a closed source drivers for linux may not be avoidable. Happy to take recommendations on GPUs!

Since I also host a myriad of self hosted apps on my desktop, I know I'll need to beef up my RAM (I usually go the max or at least plan for the max).

My main requirements:

• Intel i7 processor (I've tried i5s and they can't keep up with what I code; I know i9s are the latest hotness but don't think the price is worth it; I've also tried AMD processors before and had terrible luck. I'm willing to try them again but I'd need a GOOD recommendation)
• At least 3 SATA ports so that I can carry my drives over
• At least one M.2 port (I cannibalized a laptop I recycled recently and grabbed the 1TB M.2 card)
• On-board Ethernet/NIC (on-board wifi/bluetooth not required, but won't complain if they have them)
• Support at least 32 GB of RAM
• GPU that can support some sort of ML/AI with DisplayPort (preferred)

Nice to haves:

• MoBo with front USB 3 ports but will accept USB 2 (C vs A doesn't matter)
• On-board sound (I typically use headphones or bluetooth headset so I don't need anything fancy. I mostly listen to music when I code and occasionally do video calls.)

I threw together this list: https://pcpartpicker.com/list/n6wVRK

It didn't matter to me if it was in stock; just wanted a place to start. Advice is very much appreciated!

EDIT: WOW!! I am shocked and humbled by the great advice I've gotten here. And you've given me a boost in confidence in doing this myself. Thank you all and I'll keep replying as I can.