For a typical new install, the outdoor unit contains the charge and unless your lineset is unusually long, you just use that, releasing it with the valves after installing and leak-checking the lines.
In the US, you can get your EPA 508 cert online in a couple hours and buy the refrigerant online. (You need the cert to be legal, but it’s not really checked just to buy.) Tightly regulated is not true in practice. You could buy some in 3 minutes online and have it Monday.
s/508/608/
Yes, in the US I think it's fine; you have a lot more freedom.
In France, access to the gas technically requires a certification that is not available to regular people. You need to be professional and bow to the bureaucracy.
I know somebody who was required to pay the full installation price for a heat pump he installed himself because there was no professional that was willing to charge and launch the installation for the small fee it should require.
This is the hypocrisy and value-destroying behavior of EU collectivist governments. They tout ecological solutions, but you need to pay far more than is reasonable for those modern solutions. Predictably, people chose things that are worse but cheaper, like wood-burning stoves or pellet stoves.
Those things are made artificially expensive for no good reason, and that's because they get built overseas mostly, and this happened because of regulations in the first place. Then they wonder why the EU is losing ground economically…