What can I do with the kids this summer?

I babysit 2 boys (9 and 11) all day, 5 days a week. All they ever want to do is play video games, play on their phones, and watch YouTube videos. If they don't have a screen in front of their faces, they have a full on meltdown.

They do go outside sometimes or over to the neighbor kids' houses to play (probably playing video games the whole time), but I'm trying to come up with things I can do with them this summer so I'm not just sitting around the house doing nothing for 2 months.

I have been watching them for 5 years and used to take them to the park all the time, but they are no longer interested. I took them to the park last year and they just walked around for a little bit, not knowing what to do, then sat on a bench for a while throwing a fit because they wanted to go home and play video games. I don't know what to do. Their parents don't really mind all this screen time, for the most part. This is just how they have been raised.

I thought about taking them to my neighborhood pool, but they just don't listen very well and I feel like it would stress me out more than it's worth. I don't have a whole lot of money (and don't get paid well enough) to go out and do things all the time either.