Help: Personal Brand - Domains vs. Subdomains

I am a ML-Engineer and currently trying to bring my thoughts to reality. So I am learning web-development. I created a portfolio site under the domain: daniel.schroter.eu and thought about deploying my projects under the subdomains (current project aionepager.schroter.eu).

I thought that subdomains are treated as seperate domains by google (so no seo disadvantages). And I liked the idea of using using subdomains to help in builduing a personal brand. Everything is related and it gets clear where the projects comes from. I can further connect everything under the parent domain and link to the individual projects.

However, when looking at the search results on google I perceive that the parent domain: schroter.eu is always ranks higher or seems to be more present. The Subdomains appear under the parent domain in the search result.

So I am wondering whether this makes sense. Do you use seperate domains and if so why? What are the pros and cons ? As I am new to this I would love to hear your opinions!