Is there an app for it or is it strictly website based on mobile?

it is Strickly Web Based.
all shows are Streamed to your Device.

Also are the shows locked to the version

The Mobile shows are not the same as the desktop shows.
While the Models and Cards are the same, the shows are re-created for Mobile so that the Model remains centered on the screen.
Not all of the Desktop clips work well for this, so the Mobile clips are all re-encoded just for the Mobile Platform.

Mobile is Subscription Based.
One Price unlocks EVERYTHING.
for one low Monthly price, You get full access to every show available on the Mobile Platform Except for the NFT shows.
You also get full access to the Mobile version of the VR 180 shows.
The Photosets and the Bonus Videos.

You MUST own the NFT card to be able to see the Mobile Version of the NFT card.

like would I be able to watch the shows I got on desktop on my phone?

Since the Mobile Subscription Unlocks ALL of the cards.
Every Desktop card that has been converted to a Mobile card is Available to watch.
you Do not need to Buy a Desktop card to watch it on Mobile.
Every card available for Mobile is Included.

The Opposite is not true though.
the Mobile Subscription does not Unlock any of the Desktop cards.

Think of the Two Products as totally Separate from each other.
They only Share the Same Model Names, and Card Names.

Mobile is Subscription based.. No credits to buy, no cards to unlock with the credits.
One Price gets everything.

Desktop is Credit based, and each card is Unlocked by using credits.
Cards on the Desktop have no affect on the cards on the Mobile Platform.