Wandering Trade Underground Variant

This variant of wandering trader would spawn very rarely in caves. It will not spawn in existing chunks but new chunks only. With this wandering trader you would be able to trade cobblestone, and cobbled-depslate as well as the non cobbled variants for special items. You would need a certain amount of cobblestone like 64-128 for a diamond or 8 for an iron ore. 4 could be traded for a coal when in the deeper areas of the cave for example. The diamond trade can only be done like 1once or twice by the stone trader but the iron one maybe like 10 times and 20 for the coal one. Maybe like 12 cobble for a gold ore and 16 for an emerald. Then if you have regular non cobbled stone or deepslate you can maybe trade for miscellaneous items like a lava bucket for like 16 stones or a music disc for like 32 stones. Maybe for 64 stones you can get the disc 5 if it spawns in an ancient city in a special room of some sorts. Maybe they should add a new disc that you can only get while trading with the stone trader. Maybe he should sell redstone for 3 stones or lapis for six to help players get better redstone equipment or armor. Perhaps he can be used to help build railed mining areas by supplying unlimited rails and minecarts for 2 cobble per rail and 2 stones for a power rail. To make it not op you would have to buy the rail trade a bit before the powered rail trade can be bought again. Than you would be able to make a strip mine with rails inside without wasting any unnecessary iron anymore.