Meanwhile, I found the placeholder feature which works good.
Still I think this is not convenient as store the otp code in clipboard because of the non-standardization of the otp field’s name/id.
With the current solution, I have (for each new service) to :
check the name / id of the otp field
put them in the Kee whitelist + in the Kee tab in Keepass
With the 1Password solution, it’s stored in clipoard so I have just to +V. Et voilà.
Sounds like what you’re asking for is the ability to tie basic scripting to the end of the autofill process (whether that’s exposed to the user or not). That doesn’t seem like a simple implementation, but it could be usable. And admittedly, I’d use the copy OTP side of it for things like steam, which uses an entry style placeholders can’t (currently) work with.