More here: https://docs.oracle.com/en-us/iaas/Content/FreeTier/freetier...
I need to email the customer support to make an account and even then to change my account to PAYG account, I need to register the credit card again, they keep rejecting my credit card even though that is the same credit card that I used for my account and the test payment go through.
After that I just give up and go with Hetzner (same you need to email CS) but I can start paying them immediately after the account created.
(Disclosure: one of the co-founders, though I no longer work in the business.)
European based too which helps for some projects (GDPR etc) - though you can spin up instances in all the usual global regions.