I don't have much experience with those. I only do r134a and r12
If the system is opened to ambient air, i'd pull the whole thing into vacuum, and add oil with the Freon when you recharge.
If it's a new system (compressor) then you probably need to add oil, but I don't know for sure, some new compressors come pre-oiled nowdays.
I'm just not sure how it's going to work without pulling it down to vacuum, all that moisture in there..
i'd def go with a receiver/dryer, not sure how it'd work without, but i'd need to get my hands on it to figure it out.
I can do cannabis diagnostics over the internet but not tech stuff very easily