RPM filter is the best thing after sliced bread? Perhaps yes, perhaps not. Anyhow, INAV 2.4 allows you to use RPM filter just like in Betaflight with one difference: it does not work with bidirectional DSHOT, so separate telemetry from BlHeli_32 is required.
The most important setting is, of course, rpm_gyro_filter_enabled that switches everything ON and OFF. For the rest of the INAV RPM filter settings, you will have to watch the whole video.
INAV ESC Telemetry complete gu