It is true that you cannot go to those so-called big piano shops to learn piano. Instrument training in those piano shops is incidental and not the main business. If you want to learn something, go to a specialized training center.

I know a training center. You can ask about it, Nantong Tiantian Xiangshang Music Training. The guitar teachers there are very responsible. There is a teacher named Zhu, who is very good at classical guitar; there is also a teacher named Xu who specializes in pop and electric guitar. He used to be an arranger and is very good at improvisation. I took a guitar trial lesson from them last time, and the teacher was very attentive. If you are interested, you can search online. They have videos of students.