Joseph, the v1.7 binary from upstream SoftRF did not yet support the M5, you need to compile the latest sources. I am using arduino-cli, this is how the command looks like:
- arduino-cli compile -e -b 'esp32:esp32:esp32s3:PartitionScheme=no_ota,CPUFreq=240,PSRAM=enabled,FlashMode=qio,FlashSize=4M,DebugLevel=none,CDCOnBoot=cdc,USBMode=default'
Furthermore you need to add to ./software/firmware/source/SoftRF/src/driver/EPD.cpp (somewhere around line 95)
Then you can upload the new binary using the meshtastic web flasher and it should work.
I am still struggling with properly configuring the GPS which is a AT6558 but is detected as an L76K but the default configuration works for the moment.
Generally speaking, I second Moshe's point about the minor benefit (besides WiFi) of the M5 compared to the T-Echo or the M1.