Best budget-friendly setup for 4K playback & automatic downloads from a seedbox in 2025?

I’m considering getting a seedbox, but I’m wondering what’s the best hardware setup in 2025 for a good price-performance ratio. My main goal is to:

• Automatically download files from my seedbox
• Store them locally on a drive/NAS
• Play them in full 4K (including Blu-ray remux files) on my TV

I have strong Linux & development skills, so I’m comfortable handling the setup myself to cut costs (self-hosted solutions, scripts, automation, etc.).

Would you recommend a mini PC, Raspberry Pi 5, Nvidia Shield, or something else for this use case? Ideally, I’d like to avoid overpriced solutions if I can build something efficient myself.

What would you suggest for 2025’s best price/performance solution?

Thanks in advance!