What can i see with a 10" dobsonian

Good question and yes to seeing detail at Saturn and Jupiter. I use a 90-mm refractor telescope (since 1991) and an Orion XT10i mounted on a dobsonian (since 2018). Easy to compare the views :) The 10-inch Newtonian reflector shows brighter images and fainter targets than my 90-mm refractor telescope and I see more moons at Saturn in the 10-inch vs. 90-mm refractor. Typically, I can see 5 moons at Saturn near the rings, the 90-mm refractor shows typically only 2 (Titan the brightest). The Cassini division at Saturn in the rings is much richer view using my 10-inch at 214 or higher power. Jupiter and Saturn at 100-300x can be spectacular views, just like many globular clusters, M13 in Hercules for example. I use the 10-inch with a 2-inch eyepiece too, not just 1.25-inch eyepieces. M31 is spectacular seeing in my 10-inch compared to my 90-mm refractor telescope. You may want to invest some time and money into planetary filters too for looking at the planets and a moon filter. The Moon, Jupiter, and Venus can be quite bright in a 10-inch view, even my 90-mm refractor telescope too.

If you are using a 10-inch Newtonian telescope, keep the primary mirror (and secondary if needed) clean and your eyepieces. I clean mine every year and collimate. Know how to collimate the instrument. Newtonian telescopes take more care and feeding for excellent viewing. My 90-mm refractor can view objects down to magnitude 12.0, the 10-inch 14.0 on the apparent magnitude scale. However, this depends very much on how much light pollution you must contend with.

Another note. My 10-inch Newtonian on the Dob mount weighs some 56 lbs. The Dob mount near 30 lbs. (it has a good, large handle for transporting around). If you have a large tube for your 10-inch (like I do), get a good large carrying case to lug it around :) Add eyepieces and I may haul outside some 70 lbs. or so of equipment with my XT10i for setup. The 90-mm refractor telescope sitting on top of a Vixen Porta II alt-azimuth tripod is much lighter and easier to move. Also, very easy to remove the telescope tube (attached by tube rings and dovetail plate) from the tripod mount and setup quickly again too.
Dec 29, 2022
I would make a poor astronomer. My college mate had a 6" reflector. And every time I got my hands on it, I turned it earth bound. So much more to see. Like the lice on a pigeon at a thousand yards.

The glass was advertised as being able to see blood flow thru an insect's wings. But I could never find the right insect.

With 10" of glass I would say one could see just about anything one wanted to. Or needed to.

That's a whopper.

Later that year I microwaved an in flight sea gull. Gave up on optics and went with radio.
Another key point is to have motorized tracking. At high enough powers to see detail, the object won't stay in view very long. Dobson always had folks use Teflon pads on the bearings so the scope could be moved by hand without jumping around. I've never tried it, I have 6" scope on standard equatorial mounting and no drive. It is not really useful in sky viewing at higher powers. Try moving it by hand and it jumps too far.
Rod's point about weight is important, IMO. I have an 8" and it is just the right weight so that I'm no discouraged to take it outside and have fun. I had a 16" Dob that became a lot of squeeze for the juice. So, I sold it and glad I did.

More than an 8" will not greatly improve the quality (resolution) of what you see. In ideal seeing conditions, it will only improve it by 25%, which would be great except you may never get such an atmosphere. So expect the same resolution as the 8".

What the 10" will improve the most is its light gathering ability. It will give you 56% more light for point objects (stars). You won't, surprisingly, gain any surface brightness of extended objects (e.g. planets).