I use a mix of few things

• kapus.app for starters where a device is completely new and I need to pass some secrets like login to Nextcloud to get keepass or something
• Nextcloud - documents that I rarely access. Some bigger files
• syncthing - for often access files like main keepass. Home server acts as a de-facto hub.
• quick share for an airdrop replacement
• if quick share is not working for some reason I also have a private channel on matrix where I can share some stuff quickly as-hoc