Donchian Channel is simple to code in MQL5.
If you are trading forex then you must learn how to code indicators in MQL5.
MQL5 has been developed very similar to C++.It is infact a subset of C++.
So if you are really interested you should learn C++.
If you have been reading my posts, you know how limited MQL5 is especially when it comes to AI.
If you want to implement Artificial intelligence like machine learning and deep learning in MQL5, you will be frustrated.
The best solution is to connect C++ with MQL5 with a DLL.
There are many powerful machine learning and deep learning libraries in C++.
For example we can use Google's Tensorflow API to develop deep learning models in C++.
MQL5 C++ DLL will pass MQL5 data to C++ deep learning model that will then return the results to MQL5.
Coming back to Donchian Channel, it was developed in 1960s by Richard Donchian.
It plots the high and low over the last number of bars which is usually 20 periods.
You can read this post in which I explain in detail how to code Donchian Channel in MQL5.