They offer an app version on their website that does not depend on play services¹. I've been using it on a "google free" lineageos for quite a while (years?) an

They offer an app version on their website that does not depend on play services¹. I've been using it on a "google free" lineageos for quite a while (years?) and it works very well. [1] https://signal.org/android/apk/ https://signal.org/android/apk/