Attitude q estimator or get altitude on tiny PX4 targets

Can someone tell me the easiest way to get rel altitude display on QGC with small target e.g. Whoop with Omnibus F4, Baro is available and enabled?

The final goal is to be able to check the approximate altitude and possibly with GPS the glide path of water propulsed airplanes in the PX4 Log Review. The whole thing including lipo must weigh less than 10 grams. There is already an Omnibus F4 running PX4 and a UBX GPS module + ESP8266 available, which are light enough.
Now it’s just a matter of getting PX4 to log Altitude Rel and GPS flight data.
With Pixracer it all works but has way too much weight to work … QGC logs and shows altitude rel and all desired GPS values. Omnibus F4 neither shows altitude nor is the GPS module recognized in any UART setting only imu/hud works. Analyze shows only valid altitude_monotonic values. And including LPE in cmake gives lots of errors.

as soon as a compass is connected (unfortunately due to lack of space very difficult to realize at tiny-whoops) EKF can be selected by estimator group that adds altitude display / alt hold.
For testing that I connected a gps module with compass that weights more than the whole plane …

The GPS uart6 port of omnibus f4 sd seems to be inverted (measured with oscilloscope) is there an easy way to get it non inverted?