The ESP32 series of microcontrollers feature a lot on these pages, offering as they do a significantly powerful processor and in most cases, wireless connectivity. One recent member of the bewilderingly large family is the ESP32-S31, It’s a dual-core RISC-V unit with WiFi 6, and if that’s not interesting enough there’s the news that it runs Linux. Not -nommu Linux, but the full-fat version, as it has a memory management unit.
Before you imagine a superlative experience, it’s worth the reminder that the available resources will not give it much when it comes to computing power. But there’s an Espressif GitHub repository, and work on a port of a 6.x kernel, so you should be able to do something with it. A quick look on AliExpress finds dev boards at a range of prices, so the cost of experimenting shouldn’t be too high.
This moment at which the paths of microcontroller and full-fat SoC start to cross has been on the horizon for quite a while, and it’s exciting to see it finally arrive. Expect more similar chips in competition with this one, and more power too. Meanwhile see our noting the launch of the S31.

Any $5 USB LTE modem also runs Linux, so what?
A usb lte modem is not a microcontroller… if you don’t understand the difference, this probably isn’t the site for you