I’m quoting the page that I linked from privacyguides warning
These messengers do not have Forward Secrecy, and while they fulfill certain needs that our previous recommendations may not, we do not recommend them for long-term or sensitive communications. Any key compromise among message recipients would affect the confidentiality of all past communications.
Based on privacyguides suggestion page itself, SimpleX chat would be the next in line you can try.
Briar is only for Android AFAIK. Matrix/Element does offer E2EE chat/vid but, based on the page, it’s not recommended for long term sensitive use.
Regardless, with the current situation against encryption, any app that stays will be subject to similar conundrum about leaving/abiding the law like Signal. The ones abiding may need more scrutiny, of course.
Never tried it, but I would assume if you do a Google takeout of your Google Photos, the metadata would still be kept, and then you can upload that to Proton. Have you tried that yet?