Thanks for posting in the Community, @lindsay-masson27. 

Currently, the option to give view-only access to a user on the customer transactions is unavailable in QuickBooks Online (QBO). I can see the value of having this feature as it helps you restrict the user from editing them.  I've attached a screenshot below on what are the available tasks they can and can't do in the program.

For the time being, you can visit this website: QBO Blog. This is the place where we share our new features and product innovations. 

I'd suggest checking out this website: User Types. It helps you learn more about the different user types and levels of access in QBO. 

Also, I recommend going to the Manage users page. From there, you can edit the user access rights, view their activities, and delete them. See the screenshot below for your visual reference. For more details, visit this article: Add, Delete, Or Change User Access. 

Please know that you can count on me if you need anything else. Take care always, @lindsay-masson27.