inReach to inReach Messaging?

Hi. I'm new to Garmin handhelds & am debating which device(s) to purchase.

If I get 2 inReach mini's, can I use the inReach to inReach Messaging without a subscription?

And, if I were to get an inReach mini and a GPSMAP 66i, can I use that same inReach to inReach Messaging between those 2 models?