We've had this in Oz for about 15 years, the Private IFR Rating.
You get tested on the aspects you want to fly, the most basic is just enroute IFR with VFR at departure and arrival ends, and at the other end of the scale you can do everything that a CIR allows, except for a commercial operation.
I held one for many years, because of a couple of advantages - the machine I flew was the only one in country, and it was ridiculous trying to find a testing officer every year for the renewal - the PIFR lasts for 2 years.
The renewal was also categorised as a "Review", not a test, so if any sequence is not up to speed, it was repeated with instruction until satisfactory, rather than an instant fail and go home.
The PIFR copped flak because it wasn't recognised by ICAO, but now it just might be.