KISS
Wow. You are just starting out, ask for the time, and find yourself in a clockmaker's convention! These people are all experts, and have a lot of experience behind them, but perhaps it might be easiest to start out the "usual way" then move to the more advanced tricks.
The short answer to your question is: Yes, you can find bushings that work for multiple pens with the same tube size. The pens that can share bushings are almost always in the same "family" and look very much alike. It isn't common between pens that are not "look alike" in style.
Try the IAP app in your iPhone or Android phone. It costs $0.99, but pays for itself quickly. It has a database full of bushings and their sizes, and you can search for pens that match a given size. Don't be surprised when they turn out to be variants of the same pen.
The others are concerned about damage to bushings and losing accuracy. It is true, but way overblown. One extra sanding makes more of a difference. If you can get that good with your turning and sanding that you notice an issue with your bushing sizes, you are past the point where you need our help. Trust the bushings and your pens will be fine. You will learn how close you need to come to the bushings before you start the sanding and finishing process.
I take the metal bushings off and switch to plastic bushings for sanding and finishing. That way, your metal bushings last longer, and you don't risk getting metal bits in your wood. Just be careful to avoid rounding the sandpaper over the ends of your pen blanks after you carefully matched them to the bushings. I use these:
https://www.rockler.com/non-stick-pen-bushings-for-ca-finish
A digital caliper is a handy tool for measuring bushings and also your turning accuracy. Sometimes the pen parts don't match the bushings perfectly, and a caliper helps, but that is a lesson for another day.