Don't know where OP is located, but some UK providers (for example EE) have had plans that allow roaming in Europe and North America without extra charges.
I am located in CZ and the local providers has ridiculous prices for everything (voice, sms, data) in US. It is something like 10-11$ per megabyte of data and around 3$ per minute
The news is not so good. Both AT&T and T-Mobile used to have plans for a basic phone with a US number where for a flat $ fee per day you could have unlimited voice and texts (but no data except when connected to a wifi network), only payable on the days you actually used the phone; but those days are gone. Only monthly plans now.
Shoot that is what i was afraid of
I knew I saw some prepaid plans without contracts on AT&T website the only downside was that I needed to visit the store and set it up with an agent, but now even this option is gone
Really weird that in 2023 it is a big problem to have temporary US number with eSim and data.