No way to predict. If you're in a hurry, you might check online or brick/mortar retailers such as REI or Cabelas.
I did check my favorite online outlet (thegpsstore.com) because they typically show expected dates for backordered items. They list the Mini (orange) as backordered with an expected date of 12/10/2021. Black is in stock. Explorer+ also backordered with an expected date of 11/12/2021. Montana and 66i seem to be in stock. YMMV.
Semiconductors are in short supplies and it affect many industries, like computers, cars, etc Companies tend to prioritize the most profitable products given production shortages. For cars they will produce the higher-end models and know they likely will up-sale customers to buy them anyway. Who knows what's happening in the case of the InReach products.
