My takeaway is that unless a sealed system job is going to pay $800+, I'm not going to touch it.
I sat through a 3 hour training on R600 systems, that was 80% safety precautions.
Also, FWIW, it takes another $3K+ worth of tools because everything requires crimp connectors and no flames or heat and static dissipation technologies and new charging equipment and new procedures and pretty much new everything.
Also every single part in the machine needs to be the correct OEM part. No more generic replacements even out of warranty.
I suspect that anything needing a sealed system repair is going to just be a swap-out by the manufacturer.
Oh, also, the total charge for a domestic refrigerator is less than the capacity of one of my hoses, so I'm not sure how a gauge would work, since tapping the high side will immediately kill the refrigeration cycle..