Engineers make tradeoffs constantly. Document yours.
In your README or a separate ARCHITECTURE.md:
"I chose PostgreSQL over MongoDB because my data has clear relationships and I wanted ACID transactions."
"I used client-side rendering because SEO wasn't a requirement and it simplified deployment."
"I didn't implement authentication because it wasn't core to demonstrating my skills. In production, I'd add OAuth."
Showing what you chose NOT to build is as impressive as what you built. It demonstrates judgment.
Career Changer Tip: In interviews, mention one tradeoff per project. It shows you think like an engineer.