For home play, outside of the PS2 versions, your options for PC are Infinitas or getting in with the people who run arcade versions on their computer (I am not one of those people so I can offer no guidance there). There’s also Lunatic Rave 2 and the BMS community, which is a much less curated experience. That could be good or bad depending on your angle.
Infinitas got an update recently and I think it’s actually good now, it’s not the cheapest experience but it is for sure way cheaper than being committed to arcade play. Infinitas is REALLY grindy to unlock more songs but that’s all IIDX is, really, so it’s whatever.
All the PC stuff is playable on keyboard (and is honestly still fun like that, just in a different way) but yeah, spending a load of money on a fancy controller is the alternative. Well, I guess there are still people running the cheaper Konami PS2 IIDX controllers through USB adapters, but I’ve heard there’s a lot of complications in getting that right. I’ve never tried it.