I use calyxos as well and have microg disabled. WhatsApp works fine, signal, telgram works great, fairemail client for emails, davx5 for contact syncing etc. I don't use any google apps expects camera app (which I have disabled data access using firewall), but I have a feeling those may not work so well on calyxos.

Only problem - which I actually think is a feature is that I don't get any notifications for a lot of apps, unless I actually open the app. I really think this is a great thing because most of these apps that use google services for notifications are just sending marketing modifications which I would have blocked anyway. I do sometimes miss WhatsApp call because the notification doesn't work properly but I have told all my friends and family that they can contact me on signal for fastest response.