No grid tie?
Sounds like additional scope of work to me.
If someone wanted me to do that, I'd offer up an interlock and generator inlet at a fee. Should work with existing solar/battery systems. I would not want (personally) a 100% off grid home that doesn't have a generator backup anyway.
I've had several homes built. I've never asked to "turn on the lights" in advance of electrical inspection or main power going in.
I'm assuming lighting is AC... But that might not be the case necessarily...
I always think I've hear it all when it comes to residential customer requests but they consistently surprise me with more nonsense.
There is a reason all of my businesses are b2b and I do my best to stay away from anything public facing, especially homeowners.
I recall in my youth as an electricians apprentice we were building a fancy restaurant. The owner wanted to see his new super high dollar chandelier lit up, we only had temp service to the building running battery chargers and such. If I recall the journeyman on the job had a waiver drawn up that we weren't liable if anything at all went wrong and it was all on him and that basically we were releasing the chandelier portion of the building to him at that point. He signed it. We got to work running a temporary whip to the chandelier, Stickers on everything said 277v... prints said it was 277v... all the other lighting in the damn place was 277v... well the chandelier was 120v and went PFFFT and all of the lamps burnt out. The way the thing was assembled you couldn't just screw in new lamps either, you had to dissasemble parts of it to be able to get to the next layer of lamps. The customer ended up having the lighting rep who sold the thing come out, they lowered it and relamped it. Argued with us that it was indeed 277v. We fed it 120v and it lit up just fine with no issues.
Things like that are why I ask a ton of questions before bringing anything online prior to complete construction. Had my journeyman not had the forethought to get the release signed the little 6 man EC I worked for would have been out of business having to pay the cost to fix the fixture.