@manddje per https://docs.microsoft.com/en-us/intune/apps-add-office365 Office being installed shouldn't prevent Visio from being installed: Multiple required or available app assignments are not additive. A later app assignment will overwrite pre-existing installed app assignments. For example, if the first set of Office apps contains Word, and the later one does not, Word will be uninstalled. This condition does not apply to any Visio or Project applications.
You do need to have the license for Visio for it to install.
It also may be more that there is an existing MSI install on the device preventing the install: If there are .msi Office apps on the end-user device, you must use the Remove MSI feature to safely uninstall these apps. Otherwise, the Intune delivered Office 365 apps will fail to install.