Since regular credentials expire and service accounts take up Bitbucket license seats, it would be ideal if this plugin better supported generic SSH access keys, or at the very least accepted a personal access token for the "Credentials (for build auth)" field.

SSH access keys work in the "Optional SSH Credentials" field today if you leave the "Credentials (for build auth)" field empty and copy/paste your project and repo names in, but of course you lose the autocomplete functionality.