I think that the current capability -- open a custom URL from VM via automate -- should cover this usecase.
A nice example on how to use it is in this fix: https://github.com/ManageIQ/manageiq-ui-classic/pull/4334
I am currently looking at extending that for other entities (so that a custom button can open a URL from a User for example).
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2019:4199