Email, I'm using the POP3 and SMTP servers of the registrars of my domains. They also have IMAP and a web interface but I'm fine to look at my mail with K9 on my phone, delete the cruft and download the messages I need. You probably want IMAP and web mail.
Photos, I sync to my laptop with Syncthing and then backup as any other file. It means that I can look at all my photos only on my laptop because I don't sync between mobile devices. Occasionally I'd like to show a picture so old that's not even on the microSD card I passed along phones but nobody really care, telling the circumstances is always good enough.
Email, I'm using the POP3 and SMTP servers of the registrars of my domains. They also have IMAP and a web interface but I'm fine to look at my mail with K9 on my phone, delete the cruft and download the messages I need. You probably want IMAP and web mail.
Photos, I sync to my laptop with Syncthing and then backup as any other file. It means that I can look at all my photos only on my laptop because I don't sync between mobile devices. Occasionally I'd like to show a picture so old that's not even on the microSD card I passed along phones but nobody really care, telling the circumstances is always good enough.