You can however buy a physical card (at a few of the major stations) then transfer it to your phone. Once it's there you still can't reload it directly, but you can use a recharge station (with cash) - just put your phone down where the card would go.
FWIW I've been using Suica on a Japanese Garmin smart watch and refilling it with Google Pay on an international card without too many problems (and before that with Apple Pay with the same card on iPhone/Apple Watch), although there are probably some gotchas (Apple Pay at POS seems to be pretty hit and miss for in Tokyo and I've never figured out why).
Outside of Tokyo you can still easily get one of the other regional IC cards [1]. They can now all be used everywhere in Japan including the Tokyo subway, provided you don't start travel in one region and end it in another.
The Japanese IC systems all use FeliCa, which not all devices support. I believe Garmin only has it enabled (unsure if this is licensing or hardware) in their East Asian models (Hong Kong's Octopus cards also FeliCa).
