If you're inclined to stay on PC, you could consider a recent model Microsoft Surface. A few months ago I looked for the smallest and lightest weight music computer for travel I could find. I got the Microsoft Surface Pro 7+. i5 cpu, 8gb ram, 128gb internal ssd, Type cover (keyboard).
The i5 version doesn't have a fan, so it's totally silent, and haven't had any overheating issue (I always have a temperature monitor running on my screen). The i7 does have a fan, and so do all models of the Surface Pro 8. It comes with Windows 11 Home. I think they are around $800 now. It doesn't fit securely on the lap when the keyboard is attached though, due to the way it stands up.
This channel is has a lot about using a Surface for music:
https://www.youtube.com/@MoltenMusicTech/playlists
I've been happy with it running medium weight projects. I use Reaper, which is generally known to be relatively easy on a CPU. Ableton may be more demanding in some cases though. The above youtube channel usually uses Bitwig I think, which I'm guessing may be similar to Ableton cpu usage, due to them both being 'live' oriented.
Added the Samsung external portable SSD T7 Shield USB 3.2 $100
I got the Shure MV88+ usb stereo mic, which also provides a headphone out. It doesn't come with an ASIO driver, so I usually use the one that comes with the FL Studio demo download (the demo can be uninstalled while keeping the driver). It's latency only goes down to 256 though. For 128 latency, ASIO4ALL or the Windows WASAPI driver can be used, but if using regular windows applications at the same time, there sometimes is a conflict, where as the FL driver is ok.
The audio from the computer can be used without an interface, just plugging into the computer's headphone socket, but I sometimes hear a faint low, but not buzzy, hum if power is plugged in. On battery it goes away. It wasn't too annoying and mostly I could ignore it for non critical mixing. No hum plugging into the usb mic though.
Earphones:
https://www.etymotic.com/product/er4xr-earphones/
Their frequency balance is very good. For mixing, I only give them just a little bass boost and a subtle tweak to round off certain highs (using Realphones plugin).