Where can I find out the VP number to see if my name is actually in the Unified ...?

On the website https://erb.minjust.gov.ua/#/search-debtors

In the corresponding fields, write your first name, patronymic, surname, RNOKPP and click search. After that, you will be shown a list of all executive proceedings against you, and its number will be indicated next to each VP.

If you are a debt collector, you must submit an enforcement letter to the enforcement service. After that, executive proceedings will be opened and you will be provided with the relevant resolution on opening executive proceedings. The number of the VP will be indicated in this resolution.