When I first started browsing for new communities that is exactly what I did. I used the browser on my Pc to have one tab with my native instance (midwest.social) and one with the instance I wanted to browse. Once I found something I was interested in I went to my instance, searched with the !community formatting twice (once to discover if need be and the second to actually get to the community). The I could go to the sidebar and subscribe.
It was tedious but helped me get involved more in other instances. browse.feddit.de I believe is a browseable list of communities if you would rather search that way.