Export account as encrypted (password protected) json file

It's convenient to have all accounts in Metamask, but sometimes I need to use just one account elsewhere.
Exporting an account as private key is supported, but handling an unencrypted private key is not the safest way.
Ideally I could export one account and store it in an encrypted json-file and then use it in some other (backend) process or app.

I know we had that before https://github.com/MetaMask/metamask-extension/issues/780 , https://github.com/MetaMask/metamask-extension/issues/1232 , but I am surprised that it is still not supported although it would be much more secure than exporting the private key.

No files, tests, or entry points are named. Start by reviewing the existing private-key export flow and the historical issues #780 and #1232. Done means one account can be exported as a password-protected JSON file that can be used by another process or app.

Written by the indexing model from the issue text.