Running only one zone of a multi zone minisplit
First I would not be posting about violating the law on a public forum. (EPA fines up to 25k for violating the 608 &amp; 609 regulations)
Yes it is normal to close the high pressure line and pump the refrigerant into the system and close the low pressure valve prior to putting a recovery system on the lines.
A licensed tech can still purchase R22 online the price has really jumped the last few years and will increase until the supply is exhausted no more can be made or imported.
Can a multi zone system function with only 1 zone attached? Possibly , some can some must be connected or at least have a loop it depends on the design.
You understand the system needs to have a vacuum on the line set epa recommends 500 millitor most techs target under 100 and verify no leakage.
Who knows if the system has enough refrigerant to run, most folks do not remove fully functional systems so it is quite possible you only have a couple of lbs when it is a 6 or 8 lb system.