In general current stable Turris OS release is based on OpenWRT 15.05. With Turris OS 4.0 (should be released by the end of the year) we will be migrating to 18.06 with 18.06 version of packages feed. Architecture is in context of OpenWRT mvebu or arm cortex A9. But binary packages might be build against older or newer version of libraries so those might not work.