It's impossible if you want to study major, because once your bones are fixed, your finger sensitivity will decrease, and it's difficult to practice your skills.
But if you want to study amateur, you can, but obviously you don't know much about erhu. Many people think that erhu has only two strings, which must be simple. But this idea is wrong. Erhu is difficult to learn. It has only two strings, and its intonation is very difficult to grasp. It is much more difficult than piano, guitar and other ones with fixed notes.
I can only practice the long bow and empty string in one month (that is, I only use my right hand). I practiced the long bow for three months when I was just learning, which was very boring. Of course, it's not impossible to play music for a month, but that kind of music is shoddy, and I think laymen can only listen to the excitement.
if you really want to learn erhu, don't just use it for a month. There is no result without giving. You should also practice in your spare time when you are at school.
If you only have one month, then I suggest you learn the electronic organ, guitar, cucurbit and other relatively easy musical instruments. (You only need to grasp the rhythm and emotion when you have a fixed tone, but you need to pay attention to the intonation when you don't have a fixed tone, which is much more difficult.)
Of course, I'm just giving an objective suggestion. As for what to learn, it's up to you to make a decision. Anyway, I wish you a happy piano learning!