An RX 6600 paired with a Ryzen 5600 would blow the Deck out of the water (3-4x depending on the measurement) for a very similar cost to a mid-range Deck.

those two parts are 330€ new for me right now.
I’d still need:
a Mainboard, AM4 starts at 50€
RAM, 16GB for ~25€
Power Supply, 20-50€
ssd 10-30€

starting at 435€
Actually, that seems reasonably competetive with the 64gb version (420€), depending on the other parts you choose (I’d not want to completely cheap out on Power Supply or Storage, so give that ~20€ more each).

I’m surprised to be honest. Nice.