For fighting games, my own custom built stick. Put this together last year to replace the Hori RAP4 that had served me well for seven years until a button cap broke off. Super happy with how this turned out. It's much lighter, I like having a detachable cable. GP2040-CE supports Switch natively so I no longer need an adapter (and I can feel the difference in latency now), and Sanwa silents mean I can practice late at night without keeping anyone awake. And it just looks good, it's on brand for me.
For everything else that is not fighting games, 8BitDo Pro 2.
I also have a soft spot for the Wii Classic Controller Pro, I miss having gates on the analog sticks. I'd kill for a modern refresh of that with L3/R3, gyro, and USB instead of having to plug it into a Wiimote.
Viable? No. It's pretty much impossible for any new service to compete with the big juggernauts. Video streaming takes a ton of bandwidth so it's one of the most expensive kinds of services to run, and it's pretty much impossible to convince anyone to switch over from the established platforms. Streamers won't move because viewers aren't there, and viewers won't move because streamers aren't there.
Every now and then a new competitor pops up because some venture capitalist thought they'd be special enough to succeed where everyone else failed, and promptly dies. No one stands a chance of taking on Google or Amazon.
People will point out that PeerTube exists on the Fediverse, but all that can really be said about PeerTube is that it is a thing that exists. If it's viability you want, PeerTube isn't there and I don't think it ever will be.