Thanks for your response. I will look for an announcement from BlackBerry, but I am 100% certain support was introduced with 10.3.3. I am the author of the free BlackBerry 10 multiCERT app which easily added Let's Encrypt support to BlackBerry 10.3.0 to 10.3.2 (two clicks). I was in contact with BlackBerry dev support during development who assured me that native support would be added with 10.3.3, but they recommended I release my app for those who wouldn't have access to the OS update for some time. Once the OS update was rolled out I personally confirmed that my app is redundant on 10.3.3 and higher.