If the router reconnects to the internet when it factory resets and it still works as a gateway, there may still be hope. You’d need some SSH host on another machine behind the router; you’d probably also need some sort of minimal VPS. You could setup a reverse SSH tunnel on the SSH host that would tunnel through the router to the VPS, then you’d be able to connect through the VPS into your network.

Honestly tho, this is a lot of work and if time is tight you might just wanna roll to a store and buy whatever cheap router you can find to limp along til you get back.

So you haven’t used it yourself and are shitting on an OS based on anecdotal evidence? "Stop making stupid assumptions”, I once heard someone say.

I use GrapheneOS and have helped other less tech-savvy people install and use it. You can just roll with the defaults and have a better privacy stance than the spyware Google puts out, or you can take a deep dive. It works just fine either way.