I am currently using https://www.tindie.com/products/philba/grblhal-breakout-board-unkit-for-teensy-41/ with the availability for ethernet.
Currently using the grblHAL-teensy-4.x/grblHAL_pb1024.zip at master · phil-barrett/grblHAL-teensy-4.x · GitHub hex for the increased planned buffer, working out some bugs with this firmware, but should be good to go.
This has increased my raster speed quite a bit over GRBL-lpc, very little stuttering with a 300dpi grayscale image @ 200mm/s. This is awesome, and could be the future for DIY lasers or refits.
I am hoping that there could be some testing/dev to use the ethernet port and bypass the slow USB Serial (which I understand is limited to 115200), up the planned buffer, or stream even faster to be able to reliably hit 350mm/s raster speed. (210 steps/mm Nema 23, hiwin rails)
They have hit 600Hz on steppers (reliably, might I add) so this is just a plea to open up ethernet support for this device!
If anyone needs help, I can try to get them swapped over to this board, but I believe we have a good future with this one! Low cost (45 for the board + 25 for the teensy[600Mhz processor!!])