Season 4 released on DVD and Bluray in Australia

Season 4 will be released on the 2nd January 2019 in Australia.

Further details including what extras are included are unknown, though likely to be the same as the US version. Based on the previous season 3 release from Via-vision they are likely to be region free.

https://www.jbhifi.com.au/movies-tv-shows/movies-tv-shows-on-sale/tv-sci-fi/12-monkeys-season-4/356594/