Sure but you still have to believe and trust Filen that they are actually encrypting your files without having backdoors or vulnerabilities. If you encrypt files yourself they can’t do anything with your files. The supposed encryption of the cloud storage provider is a nice extra layer but not a requirement.

You can just as well sync a locked zip file as long as you create a new one in a synced folder. Cloud storage is a backup to me, I don’t have to access it unless my 2 local storages were to fail.

Depends what you use cloud storage for obviously.

E2EE is irrelevant if you encrypt your files before uploading them. This can either be done with a tool like Veracrypt or Cryptomator but a simple locked .7z file is also easy to use. I just store a locked folder in my Filen account and update it every month or so to keep everything up to date.

I liked it until my docker desktop randomly stopped working. Made me uninstall docker and now I use podman instead. But yeah, pretty much the same.

https://eylenburg.github.io/cloud_comparison.htm

Turn on the filter for email about IMAP and you’ll have all your options. You’ll have to look up whether they allow custom domains though.