Wakanim voucher in which shops can you buy it?

I wanted to ask if there are wakanim subscription vouchers or top up cards like Netflix? And if so, does it sell games top and Saturn?

Wakanim has reload cards, which are available from Gamestop.

Do you happen to know that for 3 months?

And then do I have to enter the code via playstation store? Or how do I activate it?

As far as I know, only for 50 days. You enter the code yourself on the homepage. But ne instructions should be on the receipt with the code itself.