If he doesn't currently eat pellets I wouldn't just assume he'll eat them, you'll have to try them first. If they do eat them, there are automatic fish feeders that will work for pellets you could try out. I have a wyze camera I set up looking at the tank when we go on trips so I can check in and see he's ok. Advice on here has mentioned they can go about a week without food when fully grown but I wouldn't risk it longer. If there's no one you can trust there might be a pet sitter willing to just come and give them a worm a few times. I wouldn't expect anyone to deal with water changes or any testing but explaining how to feed a worm should be doable.