Everything being static inline makes it hostile to these older systems which have limited RAM. Use of float makes it unlikely that you’d run it on the PlayStation, which has no FPU.

Most of the older consoles don't have an FPU. Fixed point is king on those older systems.

Only one of the consoles listed lacks an FPU, the other two (N64 and DreamCast) both have FPUs. Despite its age, the FPU on the N64 was plenty fast and it was used extensively.

It's hand written and should also work on microcontrollers like ESP32s or Pi Pico 2. Have you tried anything like that yet?

The Pico in particular has enough RAM and supports floating point math.

Sounds interesting, but there isn't any description or readme to go by.

The README is in the header file (picophysics.h)

why not in a readme

It's common enough to just copy single-file headers into a project. Now the docs come with it.