I’m not too sure about navigating that specific app, but on desktop you can just follow a link like this one: lemmy.world/c/[email protected] and you’ll view the blahaj instance from the cozy view of your lemmy.world account. You can subscribe there and it should appear in your feeds.
Alternatively, if you’re super into queer spaces you could just create an account on blahaj to make that like your “home” instance but that wont really affect your Lemmy viewing experience much. it’s akin to creating a yahoo email vs google email: you can still send and receive all the same stuff but you just log in somewhere else