Since we are in the fediverse, I think it would be convenient to have a fediverse-wide resolvable fediverse URI scheme, that would look like so:
fediverse://
edit: Found a relevant FEP: https://codeberg.org/fediverse/fep/src/branch/main/fep/07d7/fep-07d7.md
On android, when you click a link that has an association with an app you get the choice to open the app instead of being redirected to the website.
Right now every app developer for the fediverse needs to maintain a list of instances for this.
If you had a protocol instead you would only need to specify the one.