Making your own F-Droid repository was harder a few years back, and UX client-side was bad. Nowadays setting up a 3rd-party repo is as easy as scanning/approving a QRCode (for example for Newpipe repo).
Not that i approve Signal's attitude on this topic at all, but there are (were?) technical reasons for which they would do something else. Of course, F-Droid maintaining proper LibreSignal builds in their place alleviates the concern, and that's what Signal team famously opposed. For the uninformed, F-Droid has very serious review/build process for apps and i don't think malware was ever distributed on there (and antipatterns are listed in the UI client-side).
Not that i approve Signal's attitude on this topic at all, but there are (were?) technical reasons for which they would do something else. Of course, F-Droid maintaining proper LibreSignal builds in their place alleviates the concern, and that's what Signal team famously opposed. For the uninformed, F-Droid has very serious review/build process for apps and i don't think malware was ever distributed on there (and antipatterns are listed in the UI client-side).