As Joost has mentioned, user tour steps can easily use CSS selectors to identify a target like a particular HTML block.
One simple way to create a step per block would be to use the block instance id of the particular HTML block, as it *should* be unique.
You would need to add #instance-xxx-header as the text in the selector field, with xxx being your block's id. This can be viewed from the DOM inspector, and can also be verified by checking the relevant record's id in the <prefix>_block_instances table in your database, if you have access.
Either of these in fact will work as the selector value, the first one gets the header, the second one gets the whole block: