Surprisingly very low friction. The only issue is it slowly grinds away the wood but at this rate, I will have gone through dozens of spools before the wooden rod needs replacement.
Maybe add some lubricant? Something like chain grease for bikes should work fine and keep the wood from eroding. Just check how it interacts with plastic or it might eat your mount point instead :D
If the roll breaks off while the filament is inside the printer, does it not run the risk of ripping your printer off of whatever it's on? Those large filament rolls look pretty heavy, if one rolled away on my printer the printer would go with it for sure