Burner Devices Running MS & Google Services
1. If you're Joe Q. Sixpack, you probably won't be targeted by spy agencies, unless you're required to show ID to buy your device or SIM card. If you're not targetted, you should be as secure as you were in your home country running MS & Google SW. If you ARE required to show ID to buy your device or SIM card (use cash), you probably will be targetted, in which case, either make do without the device, or, use it knowing you're being monitored.
2. If you are Tess Technician or Sally Scientist, you're probably being targetted, so do without your devices, or buy them locally and know you're being monitored. (Running Linux, or whatever non-MS/non-Apple OS won't protect you from nation-level spies, as those spies know how to exploit hardware vulnerabilities.)
3. If you are Ginny Government Worker, your government can deliver secure devices to you via diplomatic pouch.