Hi Brendan,
How long the exposures can be before star trailing appears? That depends on your camera lens. The wider the field (i.e. the less mm), the longer you get. Afterwards, with several exposures of 10-30 seconds you can stack a load of photons into one image.
Have a look at the results here.
https://www.astrobin.com/search/?sea...se_max=&page=2
As you can see, on the left hand side you have several search options. I just typed in Nexstar 5 SE... Sure, the people are not using piggy back camera+lens but use their scope. But they do stack frames of 10-30 seconds to a beautiful image. Just look at Orion...
Piggyback the camera onto a scope is actually easier. Because you have the finder scope and even the GoTo functionality for finding and framing the objects. On a dedicated camera mount like Star Adventurer etc. you don't get the finder scope nor do you have a comfortable way of properly aligning telescope/camera and mount. So that's a difficult and therefore probably frustrating setup for a newbie... especially when you're not a rich newbie.
Cheers Annette