I haven’t used it personally, but it looks like Trisquel uses a kernel similar to linux-libre, which removes the ability to load device firmware when no free firmware exists for that device. To solve that, you’ll need to use a different kernel or a different distribution. PureBoot provides the device firmware for OSes that don’t have it, but the OS still has to allow you to load it.
That’s the blob @carlosgonz is referring to - the device firmware for the Intel Wi-Fi card. Wi-Fi won’t work without it.
While I wish there were modern cards with free firmware, unfortunately there aren’t any. (The ath9k didn’t either, but the proprietary firmware was stored in a chip on the card, so the OS didn’t have to know about it.)