I haven't played with it myself but these functions look like they may prove useful.
local recipeIDs = C_TradeSkillUI.GetAllRecipeIDs();
for i, recipeID in ipairs(recipeIDs) do
local recipeInfo = C_TradeSkillUI.GetRecipeInfo(recipeID);
end
These were found in this file:
https://www.townlong-yak.com/framexm...RecipeList.lua
But looking at :
https://wow.gamepedia.com/API_C_Trad....GetRecipeInfo
There is no level check in the recipe info table
So the question is where they are getting the level reference from. Possibly behind the scene database if not in one of the api commands. The API Documentation looks to be incomplete for the tradeskills so there may be other functions/variables/data that they haven't used themselves.