These fittings rules are all to do with recovery. Most home DIYer's don't have to worry about this with freeze-12 or r-134a. The fed won't come after you. However if you decide to have work professionally done or plan to sell the vehicle they need to know that the fluid is different and need a special container of for that kind of refrigerant or mixed refrigerants to recover freeze-12. To facilitate this the government requires special fittings for each refrigerant type. I do not know if there is a standard freeze 12 fitting.

Most of these rules and regulations are to help professionals and discourage DIY'ers and supposedly save the ozone. While less ozone depleting r-134a which is 80% of freeze 12 and I assume the other component contain ozone depleters as well but are not as serious. However the government has decided that shops must recover them.

I don't believe the feds will come after DIYers unless you shine them on. Just look at the IRS and how many people still get away with not paying taxes or tax avoidance or honesty.

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My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory