Yep, that’s right.
I think this Adding an Operator to Relay — tvm 0.8.dev0 documentation will be helpful, specifically step 5.
Now you don’t have a compute implementation so you need to create this. Unfortunately I don’t know a good tutorial to do this and the best way might be to just look at the code like of the op in the tutorial above ^ 
.
https://github.com/apache/tvm/blob/main/python/tvm/topi/random/kernel.py ← has a source of randomness for dropout you can use for this.
Finally, I think @altanh might have done this before. He might be more active on the discord than here.