I’ve seen a couple topics like this one. Runs on a RPi it seems, but that’s too DIY for me.
I think I’ll go for the 11" Macbook Air, 2015 (or newer depending on availability & price).
That model is still able to run the latest OS so should cover any near future updates.
Anyone here using a 2015 MBA with Overbridge?
Steam Deck - my intention is to use it for exactly this. And it’s battery powered.
At 24 channels you’re throwing a lot of audio around, you’re either looking at an adat expander or two (audient or MOTU types of interfaces with pre expanders) or a mixer with usb audio (behringer, Allen and heath sq series or Midas) all of which gets space consuming quickly. Obviously if you’re looking to take these into an outboard mixer solving this with a mixer is not ideal. You had mentioned space as a consideration for the pc/Mac running this for you but I don’t see how you’re avoiding at best a rack of gear and a significant investment to get to that channel count unless you already have everything but the pc already
I think knowing the channel count - laptop with decent specs still makes the most sense AND if you are building a rack for an interface and two Adat expanders (I’m assuming a lot here) then you can effectively add 0 extra space with one of these assuming the ventilation works out
Anyway - Hopefully you find something elegant for you.
Depending of what you want to do, a raspberry pi with https://github.com/dagargo/overwitch can’t be beaten if you’re mainly looking after the separate audio outputs.
You can all also find very cheap < 100$ 8 inch windows tablet that could do the job.
I wont be playing 24 channels at the same time, but I do want everything hooked up. That’s where the patchbay comes in. 
If no DAW to rationalize recording separate tracks, why overcomplicate over a mixer?
I want to be able to process every channel separately, but what I don’t want is a computer and plugins to make music. Dedicated hardware is better suited for me.
Ok, stepped back and somehow missed the “need individual channels” on models that don’t have individual outs and that you’ve got a mixer already 
Look at the laptop as a patchbay with a display and saveable routings and put it in a rack drawer. Out of sight, out of mind. Do you need an output for every channel? Or could you get away with some grouping and 16 channels?
2014 Mac Book Air 11" on Montery or Big Sur.