I saw this being tested at White Sea Studios YT.
He seemed fairly impressed it with. To summarise, you get a rack style plug in and you can access remote outboard gear within a DAW. It’s going to come down to your ping to how well you could use it in real time and for obvious reasons, the gear isn’t all aviable all the time. You can book in advance though.
They have a Neve 33609N and a API 5500 and more. You buy time. It’s about £8 or so for 30 mins, lower prices the more time you buy, which is not unreasonable for mastering use.
This one was first, but afaik you upload stems, though they have a Elysia Mastering Rack! A Fairchild and a Telefunken m15.
I’ll give them both a go in the week and upload them to yt in 720p, unless I can just sort out somewhere to host wavs. I hope this catches on, because it a lot lot cheaper and easier than booking a studio and having to pay for an engineer to sit watching you.
Apologies if it’s been posted before, I did search.