To convert that to open services: Let me just post this on Pixelfed, send it via Telegram/Signal, upload it to (hmm, can someone help me here) and have it recompressed by Odysee/Peertube!
Matrix is a federated messaging app, while telegram and signal make it difficult to host your own servers. You can read their docs at matrix.org or try the service at element.io
Glad I could help :) You should also see a space in your lemmy account settings to put a matrix ID on your profile, if you want people to have a more secure contact option than lemmy DMs which can be read by the instance admins.