I would like to photograph Jupiter from one of its moons.

I learned something new today.

DPI (dots per inch) you can also say PPI (pixel per inch) is a value that you set if you want the highest quality print of your image if you don’t have a physical size limit. Example printing your stuff for an art show.

Nope!
You started out fine, but like so many other people, you’re equating DPI and PPI, and calling them the same thing. DPI is purely physical, for printing, and PPI is purely digital, for viewing. There is ZERO overlap between the two.

What’s your definition of “budget camera”? I own this one, and I’ve gotten some good low-light shots with it. It costs around $800, depending on where you go for it.

https://www.dpreview.com/reviews/panasonic-lumix-dc-fz1000-ii-review