Would that actually be decent? Even 6b models feel way too rudimentary after experiencing 33+b models and/or chatgpt. I haven't tried those really scaled down and optimized models, though!
They're decent for text completion purposes, e.g. generating some corpspeak for an email, or generating some "wikipedia"-like text. You have to know how to write good prompts, don't try to treat it like ChatGPT.
For example if i want to know about the history of Puerto Rico I would put:
"The history of puerto rico starts in about 480BC when"
lamacpp is kind of this. you give it a path to a model and a prompt. download a smallish model GGUF file by thebloke. lamacpp main exec has an interactive mode too which can function like a chatbot. i never built it on android though maybe you need android NDK