Warning: cannot set option 'rtlsdr-device-index', option only supported on PiAware or FlightFeeder SD card images

did you follow all 3 commands ?

sudo piaware-config uat-receiver-type sdr
sudo piaware-config rtlsdr-device-index 00001090
sudo piaware-config uat-sdr-device driver=rtlsdr,serial=00000978

Also see [Package Install] How to Install and Configure Piaware on Raspberry Pi OS Image / RPi point 6 if you are not using a SD image