Line Drawing on Mobile

I'm starting a project soon and was hoping to get an idea of where to start on making a line drawing game in Unity. The idea is that I can draw a line to an object, snap to that object, and continue my line. Nice to have would be 'formatting' that line to be curved based on the points attached.

My comfort level with C# is intermediate, I am primarily an artist. For reference, games line Mini Metro and Dots & Co. are what i'm looking to as inspiration. They both have fairly robust line draw mechanics.