CalyxOS on my Pixel 6a

Several A series phones are listed on the LineageOS wiki, but the A31 is not one of them

This site has a crowd sourced list of apps that includes their compatibility on deGoogled Android devices.

Personally, I’ve had very few issues with apps not working, and banking/productivity apps haven’t given me issues on CalyxOS, but your mileage may vary

This post has a table of alternate Lemmy apps

There are dozens of us!