jmcsit sucks when Apple gimps file sharing for everyone by refusing to use standards
Fixed it for you. If Apple supported RCS this wouldn't happen. But I guess you prefer to follow Tim Cook's monopolistic solution and buy them an iPhone /s.
RCS doesn't have a cross-platform end-to-end encryption solution. For cross-platform communication, cross-platform 3rd party solutions such as Signal work well.
What security issues does Signal have?
pootedesuSort of off topic but are you replying from Mastodon?