There is a lot of room for disambiguation when it comes to ICAO RNAV and RNP standards. This seems to me like RNP should be its own tag separate from RNAV and GNSS tags.
We already have a tag for this: required-nav-performance. I just added some usage guidance to this tag. Some of the questions you show are already tagged with this.
I would however be in favour of renaming this to rnp (or at least add a synonym), since this is what people would probably be typing into the tag field when creating a new question. It would also follow the style for the tags rnav or gnss, which use the abbreviation instead of the full form.