Other Purism devices have had success running Trisquel:
The Librem Mini has an Ethernet port and you can order it without a Wi-Fi/Bluetooth module. However, if you want to utilize Wi-Fi on the Librem Mini, you will need to replace the Intel WI-Fi 6 AX200(NGW) module with the Qualcomm Atheros AR9462 (QCNFA222) due to Trisquel using the Linux-libre kernel: