Your best approach would be to create a resource mailbox.
Then, for each person that needs to access the resource mailbox, you'd create a user mailbox. You can assign each user mailbox with owner permissions to the resource mailbox. In the Outlook experience for each of these users (Outlook Mobile, Outlook on the web or the Office Outlook application) the resource mailbox would then automatically show up as an additional mailbox.
From my experience, shared mailboxes and shared accounts are common in retail scenarios, where the additional licensing for F1 or E1 licensing is a significant burden, but it's the best approach forward.
Although still in preview, you can also specify a FIDO2 security key for the shared mailbox. This offers a solution for accounts that are shared in one physical location. Then, you'd share the PIN with each of the persons that need to access the account. FIDO2 authentication with PIN satisfies the multi-factor authentication requirements for Conditional Access, too.