Add some paragraphs about the family, and what they do, including their websites.

e.g., https://ceur-ws.org/Vol-3180/paper-260.pdf

As the lists get longer, it might be useful to have a 1-2 sentence summary on top of each section.
Something like:

• I'm currently pursuing my PhD on building better search engines for health-related topics.
• I've published X papers with X citations and a h-index of X (X long papers at top-ranked conferences).
• I'm working as a researcher for X years and as a freelance software developer for X years.
• I'm an active open-source developer with X repositories and X stars on GitHub, frequently working with Language X and Language X.
• I was awarded the Deutschlandstipendium and won the best paper award at SIGIR.
• I'm fluent in English, German, and many programming languages, and also like designing stuff.

The copyright symbol at the bottom of each page leads to the assumption, that content on the site would have a copyright, even though in fact, the content is released without copyright, under Creative Commons Zero license.

I would propose, changing the symbol to a copyleft symbol or removing it entirely.

The current separator | doesn't fit the portfolio's visual style.
Possible substitutes:

• •
• ·
• -
• –

Add a CV for applying for jobs. That page should be printable.

e.g., zenodo.org, tira.io, etc.

Add a slightly more detailed introduction

On desktop monitors, flowing text, like in the imprint is not very readable.
We could fix that by applying a max-width of 800 pixels to the main content element.

Include the paper written in conjunction with the bachelor's thesis.

GitHub projects could be retreived via Data Templates.

Another alternative to using your awesome bash scripts build.sh and refresh-portfolio.sh might be @netlify (homepage). I think you should stay with your bash scripts for now but maybe Netlify might be an option for another project or the project of a visitor of your repo.