Perhaps take a look on the XDA forums for community supported distros on the major brands.

Also pay attention to amount of Ram it comes with, as higher will last longer without getting laggy.

I'm interested in this for a snart home dashboard. I've had a Galaxy Tab A7 Lite that got absolutely destroyed by the Android update and now even basic UI interactions are super laggy.

I've tried to look into alternative Android distributions like LineageOS but I haven't found anything suitable yet.

Funny that it is not just Apple doing that. Samsung also and that has happen ty Galaxy. They break the device you pay'd for. But any Android device will have Android unwanted apps, vender unwanted apps and spy crap like Facebook app for UI and 3 more to keep sending Facebook all data. So if you don't connect any Andoid to a PC and remove that crap, you're out of luck. It is not just bloatware. It's spyware.

Murena Pixel Tablet

...

Google Pixel Tablet runs GrapheneOS just fine.