Hello @Repetti Pierangelo !
Well in that case we cannot make a Scoped Assigment
So there is no other way , either you compromise with a Role that will manage All SPs , or look for an alternative
An alternative for example could be a Powershell on Automation Account or Azure Functions which only the specific user can execute , and perform that single one line command to reset the SP credentials
If you want to explore this option i suggest to close this thread , ( Please mark any answer that helped as Accepted) , and create a new one. Let me know your thoughts , i will happily assist you to build this as well as the whole community will be aware of the new request of yours !
I hope this helps!
Kindly mark the answer as Accepted and Upvote in case it helped!
Regards