This is when FO4 starts looking good (again)

I hope you have the scrapper perk. What was it called? Probably scrapper. Automatically scrap all junk items. They give a little bit of crafting. And then collect all the junk you can find.

Otherwise crafting stuff is the way to go.

I think you can't scrap food items any more, so you can't cheese the levelling up with buying stuff from vending machines and scrapping the items.Different areas have different items for sale.

Smart guns are a Corpo thing. Go to the Corpo area (city centre) for them. There's a gun store North-West from the Corpo Plaza. They sell smart weapons and crafting specs. If they don't have a smart shotgun, skip time for ... um... do they reset every 24h or 48h?`Anyway, skip time, check if the inventory is different, if not, skip again. Rinse and repeat until they have the shotgun or the shotgun specs.

I think I got some smart weapons from those assault in progress things in the City Centre area as well. Not sure since I was doing a Netrunner playthrough and didn't use guns. But Corpo area is your best bet for smart guns. You can buy Tabula Rasa from any Ripperdoc. That allows you to respec the points. Try a Netrunner build if you respec. Then you don't need to worry about silly things like guns. I am now starting a gun playthrough and the guns are actually fun. I did not use almost any weapons in my first playthrough. Once I got hacks, that's what I was using. Intelligence and stealth are important in a Netrunner build.