Navio2 UART SiK radio communication w/o MP

EXTREME newb here!

I have my 3dr telemetry connected to the UART port of the navio2 and I can connect to MP, but how can I connect to the Navio2 WITHOUT MP? I want to send commands to the navio2 from my laptop possibly using my own GUI. Where do I even start? Are there any beginner tutorials for something like this? MP is so easy to connect, you just select the com port and then connect but how is it done without MP? Thank you guys for your help.

There is something, “not for beginners”: https://docs.emlid.com/navio2/common/ardupilot/installation-and-running/#mavproxy