Last I heard the Loveland amazon facility is supposed to open during the first half of this year. It looks finished from the outside but I guess work is ongoing inside. (it wasn't one targeted for delay or closure afaik).
Metro Districts are like MUDs in Texas, as you pointed out, although MUDs have greater state government regulation. For example a developer has control over a Metro District even once a subdivision is largely built out. Personally I'd consider buying in a Metro District only if it had a 20 year track record.
The FNL airport - afaik whether it will be used in the near-term for commercial flights is up in the air. Will an airline want to use an automated tower? Will the FAA allow it? I don't believe those answers are known. Nevertheless local government officials are building the facilities.
We bought in Fort Collins about 4 years ago. I can't imagine a better place in the US to live but I felt the same way about Austin 30 years ago.
As it happens, we're also "invested" in the Portugal golden visa program. We were kicking it around and then felt like it was time to shit or get off the pot when the gov't of Portugal said they were ending the program. All that ended up happening was they made it more expensive for others, and then they made it easier to qualify for citizenship and get our initial investment back. In about 3.5 years we'll be eligible to apply for citizenship. We're waiting but in no hurry to be offered the opportunity for residency...that could come within a year but I doubt we'll exercise that right. Interest rates here (visiting PT now) are like 3% for mortgages so it'd be pretty tempting if I knew where I wanted to buy.