Yes, it’s a fancy way to save a tab. I just leave the tab open. Not a feature I want, so not something I want them to waste limited development time on. It’d be nice if it were through the bookmarks interface, so booarks could save state & history the way tabs do, but that’s not what’s proposed so I’d rather not have this. PWAs are a workaround to make up for the limitations of bookmarks.
DoH & DoT still leak the domain name (and of course IP address) you’re connecting to. The domain name leak can be solved by Encrypted Client Hello but that’s still a draft and not turned on for many servers.