Thank you for your reply. I have reached out to Steam Support but the Team member informed me that they are unable to locate Steam ID information associated with usernames because "Bungie uses separate accounts and an activation system" to which Steam does not have access. Steam provided me with the Bungie Help forums link to receive further assistance. I am not sure if there is somewhere on Bungie or Steam where I can view this information myself to make an attempt to authenticate my current steam account on Bungie's Cross Save system.
Steam is not going to be able to tell you what account is linked to Bungie. You will need to have them find accounts that are associated with you/your email. Bungie.net no longer displays links to individual platform accounts for privacy/security reasons.