Probably not for ddos/security reasons. Would need to use something like nohasher to get noops.
I've had no problem for years.
Biggest issue I've had was forgetting I committed something on one device before committing on another. Then I had two branches where one had " conflict" in the name. I just deleted all conflict files and everything continued as normal. If your repo is never corrupted before syncing worst case you should be able to find and delete all conflict files.
Syncthing conflicts include the source of the conflict so you could just choose to delete all files whose conflict is from one device and leave everything from the other.
If you're worried you could just ignore your '.git' folder in syncthing since you're purposefully not committing during this. Then sync through git when you finally commit your changes on a device.
If only there was some syncing thing that would let you move arbitrary files between devices.
GrapheneOS has had better compatibility with sanboxed google services for a while now. Microg is worse.
The only way I have heard threads are expensive, in the context of handling many io requests, is stack usage. You can tell the os to give less memory (statically determined stack size) to the thread when it's spawned, so this is not a fundamental issue to threads.
Time to transfer data to one thread is related to io speed. Why would this have anything to do with concurrency model?