If you're not familiar with the Github issue list here's how it works: you can create a Github account and use it to support feature requests you like and get involved with Mastodon development.
Go to the various bug reports and feature requests and "upvote" by clicking the thumbs-up.
You can also leave a comment if you've got new stuff to add, or thumbs-up existing comments you agree with.
Click the subscribe button to be notified when people are working on it or when new comments are made.