Night is just a rule; a technicality, and yes you need the lights.
IFR is a very different issue. The plane needs to be built to fly in
IMC, which means being electrically conductive for lightning discharges, and that is a real issue if you are trying to build a dirt cheap and light all-plastic plane. Radio comms need to work when in cloud too and even "IFR certified" Diamond DA40s have major issues with that right now. You don't want avionics crashing due to static. You also need decent radio nav equipment, though that could (should, IMHO) be said for night flight, because "night" is not necessarily 5 minutes after sunset which is how most UK PPLs log their "night time"
Only a part of the IFR issue is the IFR certification of this and that and avionics... that is a problem we are stuck with for now, and is a practical problem because very few pilots will buy a cheap plastic plane and then install 50kg of IFR certified avionics. I don't know how this will be handled. A Garmin 496 works OK for IFR in practice - if you are a masochist. There is no obvious way to deal with this; IFR avionics functionality is defined for good reasons.