Hi,
thank you for your reply. I think, your VCC on the UART connector was connected to 3.3V, right?
I also made some tests with the UART interface connected to a ESP32. This received the data and and transferred it by bluetooth to SW Maps. There I could see current location. Added also and RTK service, but never seen a RTK float or RTK fix.
With an LC29H and same RTK service, I was more successful. Not sure, why LG290P did not work properly.