Send the selected text to Google Translate for iOS/iPadOS via its URL scheme. If no text is selected, the entire draft contents will be passed.
By default, this action is configured to auto-detect the source (input) language and translate it into English. Using ISO-639 codes (as mentioned in the documentation below,) you should be able to customize this action for your own use.
If you have questions, please do reach out via this Action’s Issue on my Drafts-specific GitHub Repository or by any other means.
The only available documentation (that I could find, anyway) for the Google Translate app’s URL scheme is in the form of this Stack Overflow answer, copied below.
sl= source language
tl= translation language
text= the thing you want to translate
After Success Nothing Notification Info Log Level Info