I have to use Whatsapp, unfortunately.
Are there any good alternatives to the default app on Android?
I'm worried about all the data it shares with Meta. I denied all permissions but this makes it less convenient, and the app probably still sends over the data that available without them.
Afaik there were some custom clients for it in the past but WhatsApp broke them at some point. They even randomly ban phone numbers of those who try to use the official app on a custom Android ROM. Unfortunately the most you can do is get a separate physical device just for it.