I am not sure if I understand you right.
Blueprints are available from start. No tech requirements.
Unlocking robotics alone is no use, because (in vanilla) most ingredients like steel plate, battery, electric engine unit (and advanced circuit for logistic bots) are not available, needing other techs as well. It is way too complicated to fulfill these kind of specific requests, by exhaustive search of tech tree (especially if other mods modifying the tech tree).
Generally I only deal with groups of tech, classified by kinds of science packs. This is way more clear and better compatibility with other mods.
Maybe the better way is to provide more options to different tech levels (all vanilla science packs), in a future update.