In Iron Man 2 Tony Stark (the world expert on Iron-Man armour) says that most countries are five to ten years away from this sort of technology. But in MCU terms that was about eight years ago now, so if Tony Stark's estimates were right one would expect organisations in countries like Russia, China and the EU to have just started production on Iron Man armour.
America I can understand not producing anything, they had just lost their primary high-tech weapons contractor and Shield was infiltrated by Hydra both of which which are naturally going to impede progress. That should still leave the other nations of the world able to produce powered armour though
Given the three alien and one robot invasions that have happened since then as well as the numerous more terrestrial events (especially counting the TV shows AOS alone featuring an extra alien invasion, a small robot uprising and hydra&inhuman shenanigan's), one would also expect incentive as well as available technology to have both increased. This should lead to even faster roll out of the knock off armours.
Yet so far the closest we've seen in the MCU is a few of tech from private individuals like the yellow-jacket suit, vultures wings or whip-lashes lighting whips. Where are the governments of the MCU's power armour programs?
Obviously out-of-universe they had no idea the MCU was going to last ten years when they made Iron Man 2 and it would totally change the MCU if the Chinese simply rocked up with five hundred iron man suits to blow up the next alien invasion so I'm looking for an in universe explanation.