I don’t know, I used gnome for a while and I just felt like I was using toy apps. But I think that comes down to personal preference. KDE definitly has the bigger apps like Kdenlive and Krita.

Yes, using them is probably the closest one can get to the macos ecosystem on Linux.

Have you checked out Xournal++ already?

The u-he synths are nice.

Reasonable well.

Getting plugins to install is often a big hurdle, if they are working, they work. However I think performance suffers alot. Didn’t try it on any bigger synths yet tho.

I think FOSSS shouldn’t be some kind of religion, if you like Apple, great, go for it. However if you truly value privacy (while beeing better than Microsoft, Apple still collects some of your data) and freedom it certainly won’t hurt to try out some alternatives. If you like them better it is a win-win situation, if not switch back.

Things you can do if you are interrested in FOSS, that don’t necessary need you to change everything:

• Try some software alternatives for programms you are using (LibreOffice instead of Word, Gimp instead of Photoshop etc.) This lets you search for alternatives.
• Spin up a Linux VM and try it, or try to install linux on an old laptop. -And when you do that, look into KDE Connect as it offers connectivity between devices, that even Apple does not offer in some cases.
• If you are truly into it, you can even contribute to FOSS, to make them as good as Apple products.