Yes, but you can really only do that with single characters, since your first example is an ordered group and the second is an unordered set in a capturing group. The equivalency drops off when you include more characters.
Plus, you can do things like [
, and you can’t do that with the former example. ]
I would imagine there’s a difference in computing overhead, too, but I have no idea which is more performant.
Maybe? It depends what Timeshift was monitoring/backing up. In any case, the tool you used to generate the keys I believe has the ability to delete the keys (they’re just files on your system). Look up the documentation to be sure. It’s been a hot minute since I mucked around with Secure Boot, and it’s not strictly required, so I just gave up.
That’s about the extent of my secure boot knowledge. I do hope more knowledgeable people have better advice for you!