Stable flight in gps denied environment

i am using pixhawk 2.4.8 and i am working on a autonomous drone but didn’t find out how to provide a stable flight to a drone without gps
i have read vision to pose pkgs available but they are for ros1 since i am working with ros 2 humble i want to provide local cordinates to mavros to achieve stable flight

pls provide some solutions or sources

You can use SLAM technique for Drone localization without GPS