Frontier was introduced in Japanses competitions in 2016, and is still played competitevely in Canada and parts of the USA. Altough its not (yet) a very popular format, adding a rule-script for Frontier as deck type would be easy. For those 2 reasons, is it possible to add it to the list of deck types?
In a nut shell, its rule structure is the same as modern, except only core+expansions from M15 forward are legal. Its wiki is here https://mtg.fandom.com/wiki/Frontier. It currently has no ban list.