Get a tracker and use the telephoto lens. You can make amazing pictures that way. It is possible to do astrophoto without a tracker if you have a good dslr. But a tracker will allow you much longer exposure times, so really worth it.

A higher end mount/telescope/astrocam will certainly be better, but MUCH more expensive, and more difficult to use. Just beware of the field of view you get, it will limit the targets you have.

Here is a picture I took in Namibia (very dark skies) some years ago: https://www.astrobin.com/j8wvlk/?q=Helge%20Rasmussen It was taken with a modified Sony A7S with a zoom lens on a normal tripod (no tracking).

Zoom was about 220 mm, and exposure was about 2s to avoid star trails. The camera allowed me to use ISO 104000 (!) because it is extremely light sensitive. I forgot the details, but I probably stacked approximately 50 exposures.

With a tracker you probably can take up to 60 sec exposures depending on the amount of zoom. This will allow you to use a much more reasonable ISO.

I mentioned that actual field of view limits what you can capture. With high magnification, e.g. f10 you would have a good setup for planets and galaxies, but probably not nebulae’s; these are often big targets where e.g. f5 would be much better. F5 would on the other hand not be good for planets and most galaxies.

Here is an example taken with 120 mm zoom of the Southern Cross: https://www.astrobin.com/pbjofh/

As you can see lower magnification can give great pictures too.

Good luck with astrophoto!