Comment by tga_d
Pick a decently up-to-date fork of Signal on GitHub and look at its Actions. You can also just do it yourself if you'd like, the process is effectively just doing a build in a docker container and comparing the result.
https://github.com/signalapp/Signal-Android/blob/main/reprod...
The github action finishing is not the same as "reproducibility built it", which implies verification against the official build.