The U.S. probably has over 100 RNP AR approaches now. Some are "entry level" RNP 0.3 with a conventional missed approach. (IRU not required).
Others have lower, more critical RNP values and some with RNP missed approaches. Either condition: minimums predicated on RNP of less than 0.30, and/or an RNP missed approach, require at least one IRU in addition to many redundancies required for RNP AR IAPs.
Although "regular" LNAV approaches are technically RNP 0.30, they have generous containment buffers, unlike RNP AR, where containment areas have no buffers; just 2 X the RNP value.
LPV is a different beast. It is an angular scheme that emulates ILS. IMHO, LPV is better than a whole lot of CAT 1 ILSes in the U.S., but probably limited to CAT 1 minimums without local augmentation.