Most of the alternatives (Mobapad, Hori Split Pad, etc.) I have found focus on giving a super ergonomic grip at the cost of usability when using it as a single joy-con, especially the left one (since many have a traditional d-pad instead of the four buttons).
Are there any good joy-con alternatives with: a) hall effect sticks (for longevity) b) usable as a single controller c) decent build quality d) ideally gyro and good rumble (?)
I would prefer something with more of a grip than the first party joy-cons, but still usable as single horizontal controllers.
edit: I found one option that might be good. The Aolion J20 (or the Nyxi Hyperion 2, which seems to be the same thing but marked up in price) has a joy-con like shape and is also very affordable, much less than first-party joy-cons. The only thing it doesn’t have according to one review is HD rumble. The review doesn’t show any signs of poor build quality, and the RGB looks pretty cool too. I might get that and try it out, and if it’s not very good, I’ll return it.
Here’s the guide they have. I had a couple pairs to do it for (myself + my partner’s switch) and I think the first one took about half an hour but it gets easier once you’ve done the first one. The comments that people have left as well are good if you’re stuck, there’s some techniques in there that work better than some of the stuff in the official guide.