I’m a recently converted Zwift addict. Months of icy roads sent me to it. I have my best bike set up on a tacx neo t 90% of the time. It’s a smart trainer. It’s worth noting I’m a very serious cyclist (I race/ life revolves around cycling).
As others have said you’d either buy a specific indoor bike like the wattbike, which would be completely adjustable to suit you both. Alternatively if you already have bikes a smart trainer of some description. To get the most out of Zwift, you’d ideally have a smart trainer that automatically adjusts its resistance to suit gradient, generates power, speed and cadence data (a smart bike like the wattbike would also do this). That way no matter what you do on Zwift, be it race, free ride or undertake a specific training programme you’d get a fully immersive experience. I’ve used it with just speed, cadence and power on a normal set of rollers and it felt fairly pointless (I could achieve the same without Zwift in terms of following a set training session or just riding at a given intensity).
The other thing withZwift is you’d need to factor in the 12.99 per month subscription. Also weather you have a compatible laptop or tablet to steam it on. It’d also need to be Bluetooth compatible (so it can pick up the data from whatever you are riding on, and broadcast data to whatever you are riding on). For me this meant buying a music stand to attach my tablet to. I also had to buy a Heart Rate Monitor that broadcast in Bluetooth (the one I had only broadcast Ant+). If you plan to share a smart trainer and go for a direct drive (wheel off) you’d also need to consider weather the cassette would be compatible across two bikes. You also then risk uneven chain/ cassette wear if you are swapping bikes. For that reason you may be better off looking at a wheel on smart trainer. With a wheel on smart trainer you’d really need to use a different tyre (not the one you use on the road) then the additional wear doesn’t matter. That needn’t be an extra cost, just use a ratty old tyre (that’s all I’ve ever done on a dumb trainer and rollers over many years of indoor training).
A fan is also an essential bit of kit - even when I was able to get the room temp down to 3 degrees, I still need a fan to evaporate the sweat. But that’d be just as essential for Peleton.
I’ve absolutely no idea about Peleton. I don’t know any serious or regular cyclists that use it. Most use Zwift, TrainerRoad, Rouvy or Sufferfest. Peleton seems to be aimed at folk with deep pockets who like spin classes?
So I guess it depends what you both want out of Peleton or Zwift. For me. As a racer. Zwift and a smart trainer are ace. In fact it’s been so enjoyable and the quality of the training I’ve been able to do so high (compared to my normal outdoor winter base training), I can’t see myself doing that much outdoor winter base training ever again!! Although I race in real life, I fully intend to have a crack at some Zwift racing to complement my speed/ intensity work.