As part of my degoogling plan, I opted for Posteo. Upsides are that they are recommended by the FSF [0], and they run on an open source software stack [1], and were in the business for a good number of years. Changing my old address wasn't as much of a pain as I thought it would be, I personally needed to update around 30 services.

After all this was done, I felt better, and still do after 2 years. Not sure of the other aftereffects regarding privacy and such. But I voted with my wallet, that's for sure.

[0] https://www.fsf.org/resources/webmail-systems [1] https://posteo.de/en/site/about_posteo