What I'd like is an easy way to keep my notes synced on my laptop and my android phone. I suppose I could install git on my phone and do it that way, but maybe there's a less faffy way I'm missing?
Syncthing. Been using this combination for a few months now and seems to work fine between an Android phone and a few Windows + Linux machines.
I had previously been hosting TiddlyWiki from my phone, but offline editing + opportunistic syncing when on WiFi seems to fit a personal wiki better for me.
I've been using it with termux+git on phone. My shell history has the full path to the obsidian folder and the previous git commands. So I just do up arrows and enter. Not that ugly.
I'll admit it's not as UXy as pressing a sync button
I keep my notes synced on a Dropbox folder. On my Android I use Dropsync to keep all synced changes in the local file system (the official Dropbox app supports that but only for paying users).
Try Syncthing (Synctrayzor is a nice wrapper on Win, Syncthing-Fork on Android is better than original Syncthing), if you don't want to pay for their Obsidian Sync.
As long as you can sync a folder on your phone (whether with Git or any cloud service), mobile app can open it.
Of course, you may experience some conflicts, but that's why you can pay them not to worry about that. Totally worth the price for me, though I do have a permanent discount ($5/month, as does everyone that signed up before Sep 30th).