Yep, looks like a dipstick for the engine oil.
My 790's engine oil dipstick is quite short too...and requires the side panel pulled off to check the oil. That's not so bad, but the 419 loader frame prevents removal of the side panel.
No doubt I could rig an extension to pull the stick out, but getting it back in the hole would be very difficult, if at all possible.
So, how do I check the oil? I drop the loader off but don't disconnect the hoses or move the tractor. Once the oil is checked (every 10 hours or so), I re-install the loader. I normally leave the loader off during the spring, summer and fall (since most use is mowing) and most winters the tractor only gets limited use (this winter being the exception due to those snow storms).