The battery turning into a Spicy pillow is always a Concern for using laptop as an always powered on server. So even though you will be away from it, make sure that there is a way for someone to keep an eye on it, once every week or two.
That said, I have been using a dell laptop as a desk workstation (and remote use) with an uptime of 2.5 years at this point.
I also use syncthing. And it works pretty well. There is some turmoil with the android version in light of changes so the underlying sdk. And I am not sure there is an iOS syncthing that would work as well. I actually use it primarily to sync my keepass databases, and before Immich, my photos.
The photo management Immich brings makes it a nice alternative for that use case, but either way I need to have one or more servers elsewhere managing storage so I can get things off of my phone into a system I can control.
I use Immich because I have multiple devices and multiple people uploading photos to it , so we can all organize together.
Self hosting anything also gives you a lot of practice and experience (and confidence) to also self hosting anything for others, an important skill for many to have in order to have a more distributed internet.
Revolt is kinda “centralized”. You can host your own version, but they seem to actively discourage you from doing so.
https://github.com/jgraph/drawio/blame/dev/LICENSE <-- that’s … a rather specific and recent change. Is there a story here ?
You are aware that draw.io is itself open source and self-hostable: https://github.com/jgraph/drawio ?
Seconding fetchmail. It’s configuration is quite elaborate for a whole bunch of situations. I’ve used it in a small office situation to pull email from their legacy ISP’s POP into an internal IMAP server, so they could have multiple clients sharing mailboxes. (And so they couldn’t set weak passwords on an internet-connected system :-/ )