Yes of course, it is immediately obvious on the most casual walk around the Friedrichshafen show that the vast majority of the "ultralight/sports" types are built to be flown unofficially IFR. The glass cockpits make it easy.
The gotcha (as you know
) is that once you are in IMC, there are thingies out there which can come and bite you and you won't see them coming.
Turbulence / convective wx
Lightning
Terrain
Even, as I said, plain static is likely to occassionally wipe out the fancy avionics in the all-plastic types. And you will get that from flying in almost any conditions where there are water droplets around, including perfect CAVOK VMC. I had a big problem with my VHF comms a while ago (posted the details here) due to bad bonding to the elevator, so its static wicks could not work properly, and mine is a metal aircraft.
PPL training doesn't cover much of what is needed to fly safely in VMC, never mind IMC