I learn by doing so mainly wanting to understand how a full node works. After that maybe I’ll be ready to explore other branches of it like a pruned node or go off into lightning stuff.
Discussion
The pi does okay as a full node but has trouble when attaching more functions to it like a lightning node. You'll become frustrated with its constant crashing and slow lookup times. Try a mini PC or old computer first. And, yeah, I suppose to do a full node you'll spend several hundred.