+1 for logseq and its whiteboard. It’s the reason I switched. +It’s blocks(notes/paragraphs) can be reordeded. You can pay for sync between your phone and PC. But you can use sync thing which is free and once you set it up it’s pretty much set and forget. I tried obsidian and anytype, but logseq just clicked for me.
+You can write with a stylus on the whiteboard if that’s your thing.
Try handbrake maybe https://handbrake.fr Might not be exactly what you want but something to look at while you wait for other answers.
If you are actively making 4k videos through, I think it might be time for you to upgrade.
Ora.pm can do what you want I think.
Can I ask why your trying to drop nextcloud? I only really hear people raving about it. Been considering setting it up for myself.
Maybe also check out anytype
I tried anytype and moved to logseq because in anytype I couldn’t reorder blocks.