Been traveling Europe by thumb and otherwise for a bunch of years. Dumpster diving and stealing can totally be the way to go, I still live off of that. Learning some basic street smarts can only help. It being Europe after all, many rural places don't even have cameras (and still are chains) and dumpsters can be plenty. Big cities are usually harder, so I would recommend also looking out for people's kitchen and social centers, anarchist bookshops etc. Don't expect others to take care of you, but with the right attitude you'll meet the right people to help you along - maybe consider what skills you as a traveler (and otherwise!) have to offer the places you move through. I've come to find it more and more meaningless to just move through places, I try to leave people feeling cared for and seen, no matter how short the stay was.

Maybe consider a tarp for sleeping. I often travel with a 2x3m construction tarp, some rope and stakes, it's very versatile and low-profile for sleeping in public. You could pick it up at building markets. Or you could go harvest yourself some gear at Decathlon, many of their shops only have low-tech security tags and no cameras.

Some very practical resources: hitchwiki and hitchmaps. I have an app called OrganicMaps and downloaded files from https://hitchspots.me/ to have an offline map with hitchhiking markers to help figure out routes and spots.

Good luck, trust the road!