I have had fun developing a Chronograph for measuring bullet speed with a Teensy 4.0 with 3.2in tft and RFM69 radio link to a Feather M0 with the 433mhz onboard radio.
Also added a Nano printer to the wireless display for a hardcopy at the shooting range. The Feather M0 was easier to setup sharing the SPI between the radio and the 1.9in tft display
than the Teensy 4.0. The other obstacle was leaning to send big endian to small endian, but the Radiohead library was very helpful. Chrono uses piezo sensors taped to the corner of PET film
for sensing the bullet strike capturing the time elapsed over 1ft spacing.