The BetterTouchTool External Keyboard: I would buy this!

I hadn’t seen this discussion before. I thought it might be helpful to specify my current set-up as it delivers much of the functionality that the OP wants, today.

I use a programmable split keyboard, the Moonlander. (I’ve had it for years; I love it.) In between the left and right keyboards, I keep a Magic Trackpad. (I have an office and a home-office; I move and set this up in each place every day. I have external monitors at each location.) I use BetterTouchTool Floating Menus extensively. I trigger a top-level Floating Menu with a trackpad gesture. Other Floating Menus are app-specific. And so on with all the utility Floating Menus provide.

For me – an avid trackpad user (I use each hand on it) – the tandem trackpad+FloatingMenus gives me everything I think I could get from a Touchbar.

I have never had nor wanted a Touchbar. I have a MacBook Pro M4.

I have, but currently don’t use, a 15-button StreamDeck. I also have an iPhone. I have settled on a 5-row 3-column grid of square Triggers for my Floating Menus. In time I will program the StreamDeck to have the same basic triggering functionality as my Floating Menus. In time, I will also set up BTT-remote (or whatever it is called) to work the same on my iPhone.

I think those combinations with their broader and deeper software-controlled mutability (because of BetterTouchTool), will better serve me than a keyboard with a built-in Touchbar.

You have both hands on the trackpad simultaneously? Can you explain that in more detail?

Floating menus are great, but the concept of a touch bar or a Stream Deck is different. Here, your finger goes to an icon. With a floating menu, the mouse goes to an icon. Both have advantages and disadvantages.