I haven’t downvoted, but might be because third-party keyboards have been officially supported for many year in iOS. Your comment gives the impression they’re some kind of hack.
Thank you! No, that wasn't how I intend to mean it. If I recall correctly, the implementation was very restricted when the feature first launched in 2016. And if I recall correctly, it's not a feature which Apple would mention ever again.
Therefore, I have the impression that this is not a feature Apple would endorse much.
