foobar2000 has an ancient component (plugin) called Facets. One of its features was a list of buttons called filters. When you click one, it shows only audio files matching that filter (which can be set by any property). https://i.imgur.com/9GVf8Sn.png
The benefit of that feature that applies to Obsidian is to quickly hide all notes not relevant for the current scope. Facets hides non-matching audio files even from search and menus. You only see what you want at the moment. Sort of like mini temporary vaults.
Current workaround (optional)
You can use search, but:
it doesn’t apply to the Files view.
It is not “persistent until turned off”
Facets-like buttons free search to be used (and cleared) with ease.
The more I use Obsidian (for more than just a second brain, which is one connected vault), the more I realize how I need this scoped focus feature. Because the effort to manage multiple vaults (and syncing settings, plugins) is too much and gets harder as you go on.
I don’t want to be forced to create a new vault to have a clean list of tags, switcher results, link suggestions, etc.
I think having filter buttons like the ones in foobar2000 would be a great addition. It would help in focusing on specific notes without the hassle of managing multiple vaults or searches.