Let's take PayPal out of the view, It would be still very good to implement this, I could use it with Stripe(or any other Gateway).
Maybe even a "discount" for certain payment methods like "Crypto" so they get a 5% cheaper.
Yes, it would be already possible with Coupons and multiple products, but that would clutter the store full of duplicated products...
In general, it would be a perfect addition to IPS.
I tried adding TAX to certain Products/Payment methods, but it's just a mess in general.