There are several: iCloud, ProtonDrive, Sync.com, etc.
iCloud isn't cross platform enough
ProtonDrive is going to pull down every file to every device and act in a dumb way
Sync might be a good choice actually. I have to investigate them further
If anyone has suggestions on a reliable end-to-end encrypted solution with a lightweight cross platform sync software that doesn't force you to download all the files to your device (my Mac's HD is too small) and is generally fully featured. That won't take very much time to migrate with a trustworthy migration vendor. I'm willing to pay a premium price for it and I'm all ears.