This is a thing I have noticed in a lot of lemmy apps, there is no feature to go to a certain instance and view it locally. The closest is voyager for lemmy's website, where you have to manually change the url, and then you can view the instance you want.
Amazing app so far, hope Mr.Mayayo sees this post.
In case your primary goes poof someday
In case you want to post from separate unconnected accounts for privacy
In case you want to build different profiles that are all subbed to different content