Adding my support to this post which was closed. Although having a dropdown list is great, 1Password probably can't/won't stay on top of all the different kinds of databases available so at the least, it would be useful to have something like "other" and then type it rather than being restricted to the dropdown.
My particular use-case is that my servers are split between MySQL 5.7 and 8.0, and it actually matters which version it is because otherwise the connection details won't work.
1Password Version: 7.6 BETA-3
Extension Version: Not Provided
OS Version: MacOS
Sync Type: Not Provided