A similar alternative to Pairdrop with a chat UI: https://drop.lol/

Which type of content are you after? I have a page where I curate nice pics on the fediverse. There is some nature photography, but not only: https://kevinronceray.com/notes/pixelfav

I use markdown files + Nextcloud for synchronization. What I like about it is that I can use any markdown editor. Currently I use Nextcloup app on mobile and Pulsar or Nextcloud Web UI on desktop.