The online is active on PC. Especially at the deeper end of the pool, I think in terms of high-level players, a majority play on PC because it's a much better experience. (PC 5-bar onine is actually equal or maybe slightly superior to PS4 offline)
Hm... After playing on PC not sure about that lol.
It was so hard for it to find me a match on PC that it put me against literally the highest ranking Groh player on PC... for my very first match.