[hawski]

Maybe a solution to the problem would be a case that would provide cooling and would hide cables and adapters. The result could still be somewhat smaller than a NUC. Then you would only replace the phone once in a while and would have to cut a new screen cover. For better cooling depending on the phone you could remove the back cover.

[ghoul2]

Yes, and that can improve the situation a bit, but it quickly becomes a tail-wagging-the-dog situation. A heatsink requires very good thermal contact with the main heat-dissipating elements - the SoC, the DRAM, the flash, and the radios to be effective. None of those are easily accessible on a phone unless you are willing to dissassemble it entirely. And even then the contact with the heat sink will be poor due to the package and the other components.

An external case can help to a very limited extent. I tried attaching a large PC heatsink, and it did help, but not to the extent that made the "server" any good. I just switched it out for a 50$ RPI4 and its vastly better in pretty much every way.

[raxxorrax]

Which doesn't need any cooling. But to be fair I expect the screen to be worse than any component. Maybe not as much as the CPU at times which has a higher frequency than it should.

[zozbot234]

"Gaming" phones do this, actually. Most of them though have poor software support compared to "thin" flagship models with far more problematic thermals.