As someone who has been on and off the Degoogle train (I ran full LineageOS without Google Play at one point) and is now pretty deep in iOS territory, I'd say the main thing for me has been email.
I've used https://www.fastmail.com for a great deal of years now, which is also home to my calendar as well so there's nothing much of value tied to my Google account.
YouTube subscriptions would be annoying to lose but I subscribe to channels via RSS. At the moment, I'm using http://newsblur.com for that but sometimes I jump around RSS clients. Newsblur recently added backfilling of channel content from YouTube's API beyond what RSS feeds normally surface though which is great.
For plain text notes, everything is in https://obsidian.md compared to say; Apple Notes
One thing I would miss is photos which I currently have in Apple Photos stored in the cloud so I recently set up https://github.com/icloud-photos-downloader/icloud_photos_do... which runs nightly on a mac mini at my house and archives everything in a Backblaze B2 bucket. https://ente.io/ seems like a promising alternative in this space.
I don't actually have a good alternative to Apple Health now that I think of it. You can export backups but not automatically. I'm not entirely sure what format a lot of that data is even in.
Realistically, I don't look at it a lot, I just use some of the correlations when they rarely pop up. Something like https://exist.io/ is probably the closest that I actually used to (aspire to) get value out of but don't currently use.
The reality is that convenience is king and it's hard work staying independent from any centralised service, not to mention social pressures.
The middle ground I've accepted is still using it all but making sure you have a good escape hatch you periodically test + backups where you're solely reliant on large businesses who heavily lean on automated account banning.
I've used https://www.fastmail.com for a great deal of years now, which is also home to my calendar as well so there's nothing much of value tied to my Google account.
YouTube subscriptions would be annoying to lose but I subscribe to channels via RSS. At the moment, I'm using http://newsblur.com for that but sometimes I jump around RSS clients. Newsblur recently added backfilling of channel content from YouTube's API beyond what RSS feeds normally surface though which is great.
For plain text notes, everything is in https://obsidian.md compared to say; Apple Notes
One thing I would miss is photos which I currently have in Apple Photos stored in the cloud so I recently set up https://github.com/icloud-photos-downloader/icloud_photos_do... which runs nightly on a mac mini at my house and archives everything in a Backblaze B2 bucket. https://ente.io/ seems like a promising alternative in this space.
I don't actually have a good alternative to Apple Health now that I think of it. You can export backups but not automatically. I'm not entirely sure what format a lot of that data is even in.
Realistically, I don't look at it a lot, I just use some of the correlations when they rarely pop up. Something like https://exist.io/ is probably the closest that I actually used to (aspire to) get value out of but don't currently use.
The reality is that convenience is king and it's hard work staying independent from any centralised service, not to mention social pressures.
The middle ground I've accepted is still using it all but making sure you have a good escape hatch you periodically test + backups where you're solely reliant on large businesses who heavily lean on automated account banning.