I’m in a similar situation - I’m a (retired) Unix admin and have Linux servers at home but I’m still on windows for my desktop because of OneDrive. If you use it as intended, it works really well. I can login to my laptop, my phone or either of my wife’s PC’s and all my stuff is just there.
Yes, I’ve tried nextcloud and it’s close, but the windows sync client is (was?) broken - the upload speed throttling logic is broken and it was going to take ages to sync my data. I went to the nextcloud community and it seemed to be a known issue that know one cares about because the sync just happens in the background and it’s done when it’s done.
As I typed this I realised that if I move to Linux desktop I don’t care about the windows sync client :-) So now I’ve just got the issue that I won’t get my wife off windows and if we’re paying for 5TB of cloud storage, I might as well use it. Yes, I know there are ways to use OneDrive on Linux, but it doesn’t look as seamless and I’d be always concerned that Microsoft will do something to break it.
My issue was specifically the windows sync client - not server or web related. I turned on debug in the client and watched the logs and saw it making stupid (IMHO) decisions about speed throttling.