How is the command that you get in minecraft on the java 1.14 a diamond pickaxe where it says can break down. So if you can break things down in adventure mode.
Theoretically that would have to go with the website MC-Stacker, but unfortunately I can't tell you whether that is already for the 1.14. Just try it;)
https://gaming.stackexchange.com/questions/246297/an-item-to-break-only-specified-blocks
Works only in the Java edition
If anyone else looks over here, who comes from the Bedrock Edition, this command will help:
/ give @s diamond_pickaxe 1 0 {"can_destroy": {"blocks": ["x", "y", "z"]}}
x, y and z are wildcards for the destructible blocks
This was not mentioned by the questioner, so I'm from Java.