This is a timely coincidence for me. I started using yesterday Shortcat [1] for the Mac, and I'm very pleased. It gives you access to pretty much everything with the keyboard, not just the browser. To be fair, Nyxt provides other features such as scripting.
I really wish it was open-source. I loved the concept and the app worked in most applications (though not the best with Slack). But I have reservations when it comes to granting full screen access to an app made by some unknown developer.
I feel the same, so I simply block its network access (via LuLu), and it works just fine that way. I wish it was open source so I could hack on it and so development could continue - it's a really cool idea and works pretty well.
[1] https://shortcat.app/