The essentials for me are private email, calendar & cloud storage. Here is my post-Google setup:
https://tuta.com/ is a German privacy-focused alternative that I'm currently using for email & calendar. Easy switch, although I was already using web clients rather than IMAP before the switch.
I looked at Proton Drive for cloud storage, but their CEO Andy Yen is a Trump supporter (https://archive.ph/2025.01.15-162500/https://www.reddit.com/...), which makes me question his decision-making.
I settled on a 5€ / month VPS from Hetzner and using Syncthing instead, but this requires some minimal amount of technical skills to set up and maintain.
There is no alternative to YouTube, unfortunately.