tldr: keep your smart home seperate from your services and avoid RPI unless you need it specifically for a project
If I were in your shoes, starting from scratch, with the knowledge I have now, I would avoid a raspberry pi and get 2 computers with an Intel N100 (or N97 or N300). Sips electricity and more powerful than a rasberry pi.
A raspberry pi is fine for lights, switches, sensors, a few cameras etc. But if you are at all interested in one day using the voice assistant stuff, the Raspberry pi just isn’t powerful enough.
I suggest 2 computers because once you have home assistant set up, you’ll want to treat it like an appliance. You don’t want to take down your entire smart home because you broke Pixelfed or another service you get into and have to troubleshoot. Speaking from experience, your family won’t appreciate the smart home not working 😓.
I got an Odroid H4+ and have been extremely happy with it. I’m sure Beelink or GMKtec mini PCs on Amazon would also be fine but I wanted SATA ports for harddrives.
If you end up going with the Odroid, let me know and I’ll send you the links to the few things you’ll need to get going