Different scope, as far as I can tell from their site: they describe a multiplexer for all work, spanning remote hosts, sandboxes, CI, production systems and shared terminals. This is a Go binary that drives tmux on the machine you're already on, and every session it creates is an ordinary tmux session you can attach to without it. Much smaller bet, and it stops where tmux stops.
You don't need funding or teams to make these types of tools anymore, they are all basically engineering as marketing for running agents in the cloud, or some other value add/funnel into something that could make money.
I recommend everyone build their own. It's fun, you'll learn a bit, and assuming you work as a software engineer the dogfooding is built in. I built ouijit as my own example of this: https://ouijit.com & https://github.com/ouijit/ouijit (note that I am not trying to make money, just free as in libre AND beer)