do you actually train to be a RN in an MSN program

There are some direct-entry combination BS-in-anything-to-MSN programs, and of course you do. Did you think there was some way to get a nursing degree without learning, like, nursing?

Most MSN programs have a prerequisite of a BSN+RN license and there are those few BS-in-anything-to-MN.

Most MSN degrees are advanced degrees which specialize in a certain area and do NOT cover the basics of nursing.

Put differently if you had a bachelors in whatever, then took a MSN program, then took the boards youd almost certainly fail,

As most MSN programs are not about teaching you the basics. Of course this is why most MSN programs require you to be a nurse already.

Although direct entry MSN programs may very well be an exception. I know nothing of them

BS-in-anything-to-MN does include basic clinical nursing education, in an intensive program, in addition to the MN content. You would still need to pass NCLEX to practice, though.

There are some direct-entry combination BS-in-anything-to-MSN programs, and of course you do. Did you think there was some way to get a nursing degree without learning, like, nursing?

Most MSN programs have a prerequisite of a BSN+RN license and there are those few BS-in-anything-to-MN.

One of those "few" "BS in anything to MSN" route programs is offered at Columbia University in NYC. In fact that famed institution closed their undergraduate BSN school years ago and now only offers a dual BSN/MSN program. So they only way one is going to obtain an undergraduate nursing degree from Columbia is to have it conferred as part of an advanced practice scheme and have a previous four year degree in another major.

Columbia's NCLEX passing rates average in the low to middle 90th percentile historically for what that is worth.

Am not looking to pick a fight, just saying.... *LOL*