There’s Inno Script Studio as a GUI for Inno Setup script editing, but my recommendation is to only use that to get started. Once you have a script, it’s easier to tweak it by hand.
Updating Xojo or Plugin versions might change the libs, so depending on how you wrote your script, it could need updates when you do that. If you get clever with wildcards and delete commands, the script will need really minimal updates.
Beyond that, ISS is well documented so it’s been really easy to search for the changes I’ve need to make over the years.
There are other Windows installer builders more akin to Stuffit / Vise, but they come with price tags. I can’t recommend any of them, because my clients are always happier when I move them to Inno Setup 
You might make a thread asking for what other people are using for installers, specifying you’re looking for Inno Setup alternatives to get some community recommendations.