The key word there is rely! And as a 1st pass yes I would, just as I would trust such a statement from RAK, or Multitech, or Tektelic or iMST, or Lorix, or… or whoever of the principle GW manufacturers, that might declare it as a full LoRaWAN (vs crippled) GW… if subsequently proven to be wrong or a problem found then that can be corrected, and if you are someone who bought on the basis of a claim, ‘compatible with TTN’ then (at least in most parts of the world), the buyer has legitimate reason to throw it back at them or their sales channel and demand a money refund! And I would remind that Microchip is a principal member of the LoRa-Alliance, with a good history - indeed they were one of the first companies we worked with to start the pre-cursor to the L-A, and to develop what became LoRaWAN, and were a launch participant. Plus as you pointed out they were a key contributor to the design and tech behind the Things GW (Kickstarter edition) (as well as the core component on the TTNode!) so of any of the GW or other LoRaWAN device manufacturers they would/should have a good understanding of TTN and would get the benefit of the doubt…whether this should be your 1st port of call for a GW is another question and likely I would refer/defer to Jac’s @kersing response immediately above.