Don't worry- it is super confusing!
So prior to like 2000 or so all UK nurses were 'general' trained. My aunt for example as part of her nursing did every large specialty (maternity, pads, adult, mental health). So it is easy for those nurses to qualify as RNs in the US.
But because our direct entry course is so specialized in maternity we don't have the broad scope that US RNs do. Adult trained UK nurses are the only ones that have the scope to take the NCLEX (the exam that you need to take to be a US RN). But often adult trained UK nurses are deficient in maternity and pediatrics.
There is no bachelors prepared midwives. All certified midwives or CNMs have to have do a masters. Certified midwives are only licensed in ~5 east coasts states so you need to be a nurse first if you want to practice as a hospital midwife in Minnesota (then take a masters or doctorate to be a CNM).
The scope of practice of a CNM is so much larger though (teenagers- post menopausal) you do well women gynae clinics and you'd have full prescriptive authority. It's kinda like a UK version of a RM/junior SHO/GP (that specializes in women's health).
Anyway- I'm still learning how it works! But yeh that's my plan accelerated nursing masters for 18 months and then a two year midwifery doctorate. Then back to work!
Re. NMC pin- my move to the US is permanent so this year I was due to revalidate but didn't. Just took myself off the register from the end of this month.