Hello and welcome!
Looking at the docs, note that all the profiles are brought together into a single object in the end which are grouped by their names. So, the key sentence I think you need to focus on is:
To define profile properties, we have to group them under a profile name within the
profileskeyword.
Which comes from the docs:
https://osc.github.io/ood-documentation/latest/customizations.html?highlight=profiles#configuration-profiles
So you will need that profiles keyword when you defined a profile in another file, that way all the profiles can be aggregated into the profiles object.
So your prof1.yml would need that profiles key to then hold the prof1 key itself and the values associated with it. Does that make sense? Please let me know if not and if you’ve hit other issues I didn’t address.