What would be the general stance if I for example SSH'd into something I own and worked from there?
This AFAICT, isn't the case where I live, I usually have to sign something actively giving the the employer ownership (And usually it's scoped to the project), but I'm not sure if this is a formality
> What would be the general stance if I for example SSH'd into something I own and worked from there?
That would definitevely count as company time and company device usage.