Make sure you really need the trinocular capability. There's a good chance you don't, given how good phone cameras are these days.
Put it this way: don't sacrifice any optical or ergonomic features for trinocular support. You want a microscope first, and a camera platform second.
This is a good point. A cheap microscope camera (<$300 USD for just the camera) won't be as good as just pointing your phone into the eyepiece. We do that at work if we're only taking 1 or 2 pics because it's faster than turning the camera on and loading an app. And pics from the phone look better than the microscope camera anyway. If we need lots of images or we need hands free then we use the camera+pc.
The main downside of using a phone is you have to very precisely align the phone position and distance to the eyepiece for an image to show on the phone screen, it's easy with two hands, doable with 1 but annoying.
So if you need hands free to manipulate the object under the microscope then a camera is still better sometimes. But you could 3D print something to hold the phone at the right position if you wanted to. So it's not an unsolvable problem.
If you want super crisp microscopic images then you really need high end microscope optics and an expensive cameras.
And something else to consider, looking into the eyepieces will always look "way" nicer than any image ever will.
This is because your brain is combining both L and R images and producing a massive increase in clarity, the camera is not doing that. And obviously 3D vs 2D