I use Paperspace + Parsec for a regular Windows cloud desktop so I’m not locked into anything and pay just a few dollars per month for my gaming.
https://support.apple.com/en-us/HT208544
eGPUs are supported by any Thunderbolt 3-equipped Mac1 running macOS High Sierra 10.13.4 or later
The key is to realise that modern cables coming out of laptops are basically extensions of the PCIe bus. The bandwidth through them is phenomenal. It's entirely feasible to run an external GPU.
However, you don't really need one. I am a casual gamer who uses my laptop (got an Xbox too though), and even with the embedded GPU strategy/city building/etc type games work fine and look great. The Mac isn't a good platform if you're a capital-G "Gamer" but if you just want some entertainment on long flights and the like it works just fine. Go grab Steam and off you go. I don't think I'll be using Stadia any time soon as a consequence.
https://netmarketshare.com/operating-system-market-share.asp...
I ended up having too many glitches and lost connections and eventually moved to Shadow.tech and been thrilled with their service (though it's more than a few $'s a month).
You already have a laptop/PC. A lot of gaming can be done with iGPUs so the cost for you would be zero.
If you really want to play big titles, then you are looking at a delta of 300$ (the price of a good GPU) for 5 years, which amounts to 5$ a month.
I don’t see why anybody who has already a computer would pay more money to vendor lock-in themselves into an online-only service, one-store-only, no-mods-allowed, Internet-quality-dependent service.
I can see the appeal for people that wasn’t into computers before that, though. But still, if I were in that case, I would choose a non-locked-in platform at all costs.