Sync from External Drive with new Apple limitations?

So I am a new Eagle Filer user, and I am really enjoying it. I have initially set up my Eagle Filer files and folders on an external SSD drive attached to my Mac Mini (which only has a 256GB internal drive). Until recently (on my previous Mac Mini running Catalina), I was able to sync external drive folders to Google Drive (and possibly other cloud storage solutions). However, with my new Mac Mini running Ventura, it does not seem to work (I know the location of the SYNC folder has to be in Apple’s Library/Cloud Storage folder, but I thought until this morning that I could still choose external drive folders to UPLOAD to Google Drive online).

Any solutions? I am happy to pay something reasonable for some kind of cloud service, etc. I am backing up with Backblaze and Time Machine, but I was trying to figure out a way to access the library from different macs, and also keep it it in sync and also save internal drive storage space.

There’s a good article about Apple’s File Provider Extension changes:

It seems to say that, among the cloud providers, external drives only work with Microsoft OneDrive.

I’ve not used it in a while, but you may have more flexibility with something like Resilio Sync:

Thanks! Checking Resilio out now. It’s possible I am overthinking this. I eventually won’t be adding emails to Eagle Filer except periodically, and I could always just copy the library over to my laptop or even a flash drive at the time for a static duplicate copy of the email archive to have with me.

Out of curiosity, do you have any sync system to access your Eagle Filer database on a laptop? That syncs with a “main” desktop? Curious what the master uses!

Currently, I have an M1 MacBook Pro that is both my desktop and laptop Mac, though I do sync with a “backup” laptop. Back when I was using two Macs more frequently, I would have my most active library in iCloud Drive and sync the big ones (too big for cloud storage) using rsync. Now I still do the rsync for the big files and mail archives. For my libraries that are mostly Markdown and RTF files I use Git to “sync” the files using between multiple Macs and iOS devices.