Minecraft wiki entry for Nether_survival, associated text: Netherrack, soul sand, gravel, lava, magma block, glowstone, nether quartz ore, soul soil, blackstone and its variants, nether gold ore, basalt, crimson stem, warped stem, are all freely available. Note that while the player can pillar-jump to mine a high glowstone formation, a little exploration may reveal more accessible blobs of the stuff (look for places with low ceilings).
Crimson and warped fungus are found in crimson forests and warped forests
Red and brown mushrooms are likewise found scattered about.
Ghasts sometimes drop ghast tears and/or gunpowder.
Magma cubes can drop magma cream.
Zombified piglins sometimes drop rotten flesh and gold nuggets. They can drop golden swords and gold ingots. However, attacking these is unwise until the player is prepared to handle a lot of them.
The player can also mine nether quartz, used for advanced redstone components, and decorative purposes as well. Fortune is a true gift here.
Obsidian can be farmed with nether portals. View the nether portal for more details (the diamond pickaxes needed to mine these can rarely be traded for emeralds by some villagers, making them renewable).
Blackstone can be used as a substitution for cobblestone in the Nether, or as a good building material.
Nether gold ore can be mined to get gold nuggets, which can then be crafted into gold ingots.
Ancient debris can be used to craft netherite items.