It doesn’t meet every requirement you listed but privatebin.info supports file attachments, configurable expirey, and burn-on-read, and is fully end to end encrypted

is plasma any good yet? I last used it in like 2019 and it was too buggy. I’ve heard it’s gotten better, but I haven’t had the chance to test it

1 step forward, 4 steps back!

I don’t know, but I wouldn’t recommend OpenShot because it just gets really laggy when adjusting the timeline, and it lacks certain workflow features that you’d just expect mature video editing software to have (like the ability to move or delete keyframes)