Hi @luca590!
Honestly, I am not sure if it is legal to pass a ModuleList directly to a Sequential, but you can give it a try in a toy example!
Anyway, if it does not work, there is a simple workaround. You may define a nn.Module whose init() method receives a ModuleList and connects each Module in the ModuleList sequentially. Then, simply add the defined Module to your Sequential. Did you get the idea or do you want me to write some sample code for it?
EDIT: After taking a brief look at the implementation of nn.Sequential(), I would say that passing it a ModuleList() probably works  Please give it a try and then update me