Syncthing-Fork has had reproducible builds since the 2.0.7.0 release, despite what @ImranR98 is implying.
The F-Droid reproducible build documentation says:
Binaries is present in the build metadata.
See metadata/com.github.catfriend1.syncthingfork.yml · 71e31b2f72ae8792d83f26251178fa695b9a7167 · F-Droid / Data · GitLab and syncthing-android/scripts/fdroid/com.github.catfriend1.syncthingfork.yml at cf4714bc9d07d49b7956ad24cb2458aa6e188baa · researchxxl/syncthing-android · GitHub.