There has been some other very fast open source boards around for some time.
The older Lichee Pi For NanoFW(16M) Cross-Border Core Board with WIFI Module + TF WIFI Adapter Development Board with an ARM 926EJS running at 900MHz, this thing is the size of an SD card
https://www.aliexpress.com/item/3292936 ... b201603_53
And the newer Lichee Pi Zero ARM Cortex-A7 running at 1.2GHz and about the same form factor as the new Teensy
https://www.aliexpress.com/item/3304722 ... b201603_53
Many of the hackers like the Lichee Pi Zero ARM Cortex-A7 running at 1.2GHz because they don't hit road blocks with closed source grey blobs