Serious answer: Host your own local instance, and defederate from instances you don't want to see. The beauty of the fediverse is that because it's federated you have the option.
I regret to inform you however that you're probably not on the right platform. Lemmy is currently even further left leaning than reddit.
Because currently lemmy doesn't substitute links to rewrite them from your own community.
Eg. [email protected] would refer to https://lemmy.one/c/[email protected] From your instance. If people don't link correctly though it'll direct to https://sh.itjust.works/c/cats which you wouldn't be able to join
Essentially as long as your instance isn't actively defederated from a given instance, you can typically join your instances "mirror" of that community.
Say you wanted to join cats on sh.itjust.works... you can open your instances search and paste [email protected] into your search
Kbin is sort of like a hybrid between reddit and Tumblr though, as it also has microblogs
Solasta got a multiplayer update recently as well in the same vein.
I had a similar issue, but mine was caused by having a vlemmy account logged in on the app alongside others. Looks like if an instance closes it can freeze loading content from all other instances. This is probably a bit of a bug.