There may be a few workarounds. A VPN from somebody like Surfshark would let you watch regionally locked video content and AppleTV+ includes a 90-day trial with new purchases on new accounts. This would also apply for Apple Arcade too.

It would be a longshot but adding the US account to family sharing on your UK account might let you download premium apps the other has bought. Your contact in the USA might let you also add your new AppleID to their family sharing.

What you sadly cannot do is sideload MP3s onto it by hooking it up to a Mac which is a bit of a shame.