Apparently X-Cell did make a stealth smart phone. Interesting article with screenshots here: https://www.stealth-phones-guide.com/blog
However, the website that offers the “Android Ultra Secure Stealth Phone” also appears to be down: https://stealth-phones.com
I would love to see efforts made by Purism to implement some of the above features. Kills switches and open source hardware & software don’t seem to be enough in today’s world.