After a prolonged hiatus, I am returning to this project.

I'm working with FPGAs again and remembering how frustrating the programmers are, and why I started this project.  My previous attempt was diverted to software efforts for some off-the-shelf MCU boards.  Last time I was spoiled by working with an FPGA (MachXO2) that supported SPI and I2C configuration ports, so I was able to avoid the pain of JTAG.  This time I am not so fortunate.  

I want an easy to use programming tool that will run on almost anything, without complicated software and target a variety of devices.  Targeting a variety of devices can be simplified by using the SVF format which most FPGA tools know how to generate.  In order to simplify the use and installation, I will run the majority of the code on an MCU and communicate over USB with a virtual COM port.  Using a virtual COM port interface means you can use the default USB driver in the OS and possibly support multiple platforms without compiling apps on each.  

To keep this accessible, I want to support the most cost effective MCUs available.  Right now that would be the Raspbery Pi Pico which is one of the few MCUs you can find in stock, and the dev boards only cost $4.  A bonus feature of the Pico RP2040 is the PIO programmable I/O, which may be helpful for accelerating the abomination of a serial protocol that is JTAG. NXP/Freescale FlexIO may also work for this, but those devices are harder to find at this time.