Any Advice on taming v young feral kittens?

Asking for a friend: Another friend of hers has been leaving out food for a couple weeks. The kitties will stay in her yard when she is present, but she can’t pick them up.

She would like to tame them, litter train in her garage, and adopt out for free. All the local shelters are too full to take them.

Once tame, I suggested she sends notices via Craigslist and Nextdoor. I also had the idea that if a neighbor has a rummage sale this summer, perhaps she could sit with the kitties on leashes to find good homes.

Thanks so much for any advice.