LFM 2.5 1.2B instruct, it's good at instruction following as long as the instruction is short and simple.

Gemma 4 E2B is even better than LFM but I don't know if you can fit it in 3GB.

Qwen 3.5 0.8B and 2B are smart but very inconsistent for instruction following.

If you need absolutely tiny models, check Gemma 3 270m and FunctionGemma, LFM 2.5 230m and Granite 4.0 350m. However those are very stupid models and whether they are feasible for you will depend on your use case.

qwen3 1.7b- q4_k_m is your best best for that size