This will come in a future update 👍

I had the same issue. So far, the only solution I found was to create a separate account on each instance I want to follow.

It's not ideal, but it works.

I would like this feature as well. I'm finding it very difficult to navigate to other instances communities as there's no way I can find to browse to them, nor search for them. the only way I can seem to locate them is by accidentally coming across a community in my feed.