I've been waiting around villagers with jobs (the jobs they could acquire without workstations that require cobblestone), and wandering traders, but I'm not getting anything..
Could this be a bug?

you should read up about wandering trader spawning

a wandering spawn on average in around 4 hours in a 96 by 96 area around the player and only spawns on the top block so

Do you get other gifts?
The documentation says "Once you have the Hero of the Village effect, stand by a Toolsmith and they may gift you a Lava Bucket." So it have to be a toolsmith (needs smithing table) and you have to have Hero of the Village (so defeat a raid first).
To get it from a wandering trader you need to enable (its off by default) it by doing: /carpetskyadditions setDefault lavaFromWanderingTrader true

have received thousands of tools but no lava bucket. Hero I or V no difference

Just tested this and received a lava bucket as the 2nd gift. Make sure you have the datapack enabled (if using the acacia start, you need both datapacks) as this is a feature of the datapack. If you see the custom advancements you should be good. The lava bucket gift has a weight of 2, so it's a 1/21 chance with toolsmiths and armorers and a 1/16 chance with weaponsmiths.