You’re assuming a domestic state actor, no? I don’t think it’s a positive certainty that e.g. a foreign state will certainly be able to physically access your systems. Of course, I suppose if you send it in to a foreign country for repair, anything can happen.

If properly motivated, I don't think national boundaries are going to stop someone from accessing a physical device. There may be a small list of countries with very good border controls and lack of existing foreign agents. I'd be curious to know which ones fit