both encrypting in parallel and encrypting in the second way you mentioned are bad ideas, and are far from being what is seriously being discussed when people talk about hybrid KEMs. Encrypting in parallel is explicitly IND-CPA insecure if one of the ciphers is broken. Your construction is IND-CPA secure, but quite inefficient, and would not fit into modern protocols.

If this was a typical cryptographic topic, this might be fine, and is how I would likely phrase things for an undergraduate cryptography course. Unfortunately, this is a topic that a certain cryptographer with a decently large public following has been spreading conspiracy theories (and slandering other cryptographers about) for a number of years now. So, discussions on this topic often come from a place where the audience is misinformed, and more care is required in grounding the discussing in what is actually being discussed/considered.