Just an aside, but it may help others who have this issue to share the solution that worked for you

Not commenting on the content, but you should not dismiss an argument because it contains a slippery slope. A slippery slope fallacy is an informal fallacy, meaning it’s existence does not inherently mean an argument is flawed.

I use Duplicacy to encrypt and backup my data to OneDrive on a schedule. If Proton ever creates a Linux client for Drive, then I’ll switch to that, but I’m not holding my breath.