The "T" version is specially selected for low energy consumption and is partially throttled to help achieve that low TDP. 35W TDP is the most the 1U fanless case can handle and that's why I'll likely end up not going that route.

Apart from a few very special versions, laptops have always been significantly constrained. It just a fact of trying to get suitable bits into a compact box at a reasonable price.

Apple don't like to compete head-to-head with Microsoft and the various PC-makers. It's "race to the bottom" price strategy and Apple prefer to market as "premium". Also the end of the PC market has been predicted for a long time now, because tablet and 'phone sales surged and PC sales fell. But there are still many tasks for which a tablet really isn't suitable (e.g., trying to run a big CAD system of a tablet would be ludicrous; multiple 24" screen are typical).

Yes I'll be fine with whatever path I finally take. I'm just reluctant to waste hundreds of beer tokens on bits that don't really make a significant difference. I don't really want to go above 65W TDP as that would start to take me into fan noise in a small-ish 2U.

I use a small, old-ish notepad PC when I want compact portability (like on the boat, mostly I use headphones, I have a Q49 contoller-keyboard on board); I have a Focusrite Scarlet (and wooden case for the notepad+scarlett+PSUs) if I want better sound quality and still compact. My "stage portable" is a 6U Gator flight-case, and that's where the 2U PC goes. The preset PC in that is a mini-tower screwed into a 2U shelf, but that's a horrible hack.

Jazz relative beginner, starting at a much older age than was helpful.
AVL:MXE Linux; Windows 11
BIAB2025 Audiophile, a bunch of other software.
Kawai MP6, Ui24R, Focusrite Saffire Pro40 and Scarletts
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