Good Morning Pedro.
Please let me know whether I understand the question correctly:
In the USS-UI (and the SC-UI?), you want 'a message' to be presented to the logged-in user, when an SC-Request gets approved?
When this is correct, then I've to tell you that from within the approval process, you could send an email message.
However, sending a message to the USS-UI(SC-UI) seems impossible.
Perhaps other member(s) of the community know different.
Thanks and kind regards, Louis van Amelsfort.