Another one selfhosting contacts, calendar, notes and so on with that non-interoperable protocol.
And for the shake of honesty I need to say that while doable it is true that the situation could be highly improved with a lot of non standard stuff that private apps are implementing outside of the standard compliance
Even if you have a valid point, modern fingerprinting technics usually is done through your data and the connection dependencies of them (which accounts are activated from the sane computer and so on).
Selfhosting remove some links between your data set like the files you store in drive, the people who appear in your photos, your contact list, to whom you email… Etc etc
Suddenly all this data is vanishing from the big techs, so, in theory it would be possible to make that association process more difficult
Then follow that path, once you are comfortable with the approach you can start hosting more and more services,to the point that you can selfhost your own messenger services or ms teams services.
Once you are in that situation, you can think in accounts rotation and/or burner identities to address the services you can not pull from the big techs
You need to start reducing your fingerprint on internet.
The only reliable way to do so is selfhosting your stuff.
There are a few communities here in lemmy, so check on them
I use the tchapi docker image for the caldav server (die to the LDAP support for the user Auth) and davx5 for the android integration.
In Desktop thunderbird already have a native integration and with iPhone is also working fine.
No problems so far in almost a year, they work reliable and smooth. The only point I somehow miss is the lack of push notifications from the server to the devices, but it is not a deal breaker from me