I've been doing the opposite, started learning piano one year ago with Playground Sessions and now learning guitar with Guitar Tricks. I must say both sites are absolutely fantastic, if you enjoy Guitar Tricks you'll find the same quality over there. If you have a digital piano, they recently launched an iPad app. Some bugs must be ironed out but it works ok already.
I both the instruments guitar and piano and had the option to decide which one I should learn first. Few of my friends told me that the piano is easy to learn and that you should start with the piano. So, I started learning the piano first. I 56 and it is not easy for me to learn the piano. But I am fully committed t learning piano and guitar. I am following a piano program which was recommended to me by my one of family member https://musicgny.com/piano-for-all-review/ Currently I am on book 2 and still early days in learning. Hopefully, with time I will be better at it and will then start learning guitar.