Disclaimer: I have no experience post-covid, nor on flights other than Copa. I have never tried an I-I connection there, but I vaguely recall seeing signs for international connections upon entering the immigration area. MDE is a relatively small airport and the airside facilities are rudimentary. It's just a big waiting area with chairs and a snack bar and some typical retail shops. It's not so great landside either, but it might be a more interesting place to spend a few hours waiting. The entry and exit process is fairly efficient.