Sightly tangential, but does anyone know of any good system that integrates everything across devices? I'm talking backups/data management, clipboards, maybe no

Sightly tangential, but does anyone know of any good system that integrates everything across devices? I'm talking backups/data management, clipboards, maybe notifications too etc. Bonus if music/video can be streamed and mouse/keyboards can be used cross device. KDE Connect is nice and can do some of these, and many backup utilities like rclone or duplicati (which I've used in the past) can do some, but many features are not great. The closest I can think of is Apple's walled garden where you store everything on iCloud, but a) the massive restrictions on iOS, and more recently on MacOS (see: kext restrictions) are forced and b) it still isn't perfect and requires an iCloud subscription if you have more than 5gb of data you want synchronized. I'm curious to know if any HN person knows of such software (assuming I can run a server to host the backend). (In real life I still have an "unlimited" GDrive account from my university that I use to sync but it's far from perfect.)