Memberships in multiple currencies?
There are many ways you can do this


Create contribution page and price set for each currency. Provide a list of contribution page to user and based on currency they can use the contribution page
Create contribution page and price set for each currency. Add currency field on each contribution page using buildform hook and on selection of currency load the respective contribution page.
Create a price set with radio field and have all the currency as options with same membership type. Using buildform or buildAmount hook change the amount or field label to include currency(not necessary if can add it price field option label). On submit of 1st page set currency in postProcess hook in $form so that right currency is set to send it to payment processor.


HTH

Pradeep