It sounds like your ask is for a recommendation to back up personal files from disparate locations to a server.

I use a self hosted Nextcloud instance for this purpose.

I dislike anything that comes out of the Apple ecosystem. Keep that in mind when I say that I agree here insofar as MacOS being a better user option than Windows at this point.

That being said, I would encourage OP in their pursuit to see if Linux can fit their needs. Anecdotally, I've been using Linux (Fedora, KDE) as my daily driver for years now. I find it quite polished and have no issues with finding applications that fit my needs.

Realistically though, application support can be problematic. If a specific proprietary piece of software is required or important to you and it's not available in Linux, that could certainly be a non-starter. You could fuss about with wine and try getting that stuff working, but no guarantee it'll stay working so I wouldn't rely on that. I know OP is interested in A/V stuff. That's not an ecosystem I'm very familiar with. I know it exists, but I don't know how good it is. No harm in trying though, all it costs is time.

I have an arguably bad piece of advice, but one I hadn't seen in skimming the replies.

You could always install Windows in a VM. Libvirt and virt-manager offer a pleasant GUI experience so it's easy to do. If you give the VM a heavy resource allotment (while leaving a reasonable amount for the host) it should still perform well. The VM video driver is the only place you take a not insignificant performance hit, but for A/V manipulation I don't think it'll matter. Unless you use GPU based video encoding. In which case it'll be CPU bound now so slower. You can potentially do PCI pass through to your GPU but that adds complexity.

A big downside here is that as far as Windows is concerned, this is different "hardware" so it won't activate based on your physical device. As I recall, it only allows the use of one core while unactivated which is pretty much unusable. So a pretty hefty expense relative to a personal VM, I think. But it is an option.

You may want to pass through the audio so it's not reencoded. The top answer on this stack overflow article has an example. https://stackoverflow.com/questions/9913032/how-can-i-extract-audio-from-video-with-ffmpeg

And a copy/paste:

ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac

Relevant example, with afraid.org you can do it with a wget or curl command.