Usually 'full stack' just means software. Here it means a true Linux phone (Sailfish OS) plus Android compatibility with sandboxing. The C2 model is made in Turkey from Asian parts. The new phone is manufactured in Asia, but the final assembly, QA, and software flashing are done in Finland.
This isn't for people with a consumer mindset. It’s for people who want a Linux computer in their pocket, more privacy, and still want to run some Android apps.