Minecraft wiki entry for Redstone_tips, associated text: Redstone: There are only a couple of renewable sources of redstone: killing witches (witch and raid farms are rather slow) or trading with Clerics (which is even slower). However, it is fairly plentiful in the underground, especially once you have a Fortune III pickaxe to multiply its drops.
String: A spider farm can help if your contraption includes a lot of tripwires and/or dispensers. Piglin bartering is an alternative
Iron ingots (Make an iron golem farm if you need a lot of hoppers or minecarts)
Slimeballs: (For sticky pistons and/or slime blocks)
Honey Blocks: Used in some mobile constructions. Requires farming bees.
Stone and Cobblestone: Smooth stone for repeaters and comparators, cobble for pistons, dispensers/droppers, etc.
Nether Quartz: Plentiful in the Nether, can be renewable farmed with bartering. With it, you get to use comparators, observers, and daylight detectors.
Glowstone: Used for Redstone Lamps, or lighting. Can be found fairly easily in the Nether, or it can be purchased from Clerics or Wandering Traders. Witches can also drop small amounts of the dust.