ELRS 4.0: How to configure extended PWM limits?

ELRS 4.0 supports extended PWM limits - PWM pulse width can now be configured to go from 500us to 2500us vs ELRS 3.x's limitation of 1000us to 2000us. Has anyone experimented with this?

Where can this be configured? Lua Script? ELRS Web UI?
Can a serial ELRS receiver be configured this way, or is this restricted to ELRS PWM receivers only?
Is it possible to utilize extended PWM limits with a serial ELRS receiver and an INAV compatible FC with PWM output (eg. Matek F405 Wing v2)?
Is it possible with a serial ELRS receiver and a CRSF-to-PWM converter (eg. Matek crsf-to-pwm)