Another option is a 'maxed out' mini e.g M5 Pro/64GB. Mini is super easy to travel with if you know there'll be a 'dock' at the far end e.g office<>home or whatever.
A part of my brain can’t process acquiring a Mac Mini M5 Pro knowing that they sell M6 despite being aware that it is just a weaker processor.
It will get worse with the MacBook ultra rocking a M5 too.
Apple’s marketing department is gonna kill me.
So I can somewhat speak to this, as I actually did this for a while c. 2021 and 2022.
The issue (apart from my Mac mini still having the old, bigger form factor back then) is that this requires a full shutdown (obviously), and that is more friction than opening a closed laptop lid. It just takes a moment for every app and background service etc. to settle back in after, and depending on how your brain works, you might not like that a whole lot.
It absolutely is a cool feeling to carry a pretty mighty desktop in the backpack, though.