You can 'sit on the dog' to get the behavior. I leashed my restless stinker and sat down with a book and waited. He eventually lay down. I do use food and tossed a bit away from him so he had to get up. Rinse and repeat using the cue word when I could see him starting to lay down. With a pup you might want to work in a small closed space like a bathroom or hall so leash isn't chewed on. If he won't take treats then perhaps reward him with a short game of ball or tug. Pup lays down, happy talk and toy comes out all in the same second. Play for maybe 15-30 seconds, put toy away and wait for him to lay down again. I'm a terrible lurer but suppose you could use a toy to lure into position as well. Dogs work hard for a toy reward for recall as well. He has to have some interest in toys as well of course. Does he? I think I'm a great reward. Play keep away. He probably have fun at first then start to worry about you being away from him so allow him to catch you and give him loads of love and maybe a short game. Around the kitchen table works well, hiding around corners works well.
Do train before meals. I used to use dinner kibble for training during the day and leftovers were served at meal time. Keep sessions extremely short. I take 1" chunk of string cheese and when it is gone session is over. That's maybe 20 rewards per session. You might take a small handful of kibble and once gone session is over. Oh, rolled treats are way more delicious than ones handed to them. Get the behavior then tell him to get it as you roll the bit away from him.
Drilling is demotivating for all the dogs I've had. Would love a dog that would drill so I could practice my skills! Once you get a couple good responses move. Turn around, change your position, move to another room and so on. If he is really worried about this he might stop taking food. My dogs slow down the response I'm looking for, throw other behaviors at me and wander off if they are upset by drilling.
I had a dog that actively hated hot dogs. Empty your cupboards and refrigerator looking for something he likes. Try bits off your plate too. With dog tethered to me with a waist leash I even rewarded good leash manners with a straw dipped in my frappuccino whipped cream one time. Not good for the dog or me but he probably got 1 measuring teaspoon of that cream total. Dogs can eat most things we do but never raisins/grapes, chocolate, macadamia nuts, anything with xylitol or onion/garlic. I'm sure I have forgotten some. Remember his size and adjust the amount you feel safe. If he gets a hundred calories of treats then reduce his kibble by that amount to avoid gut issues and keep him trim.
If you are trying to train when pup is distracted move to a more boring place. I closed off the hall, bathroom can be another good spot.
Be happy. Lots of happy baby talk, praise him to the skies when he sits or gives you attention. If you don't feel a complete fool you aren't being silly enough. Yes getting him to be a well trained dog can be life or death but training him has to be a bonding happy experience.