I have a big project using other UI which has a big portion of it using the GWT canvas and if I am thinking to use the domino-ui I prefer to keep the GWT canvas code.
Yes you can. Either you use elemental2 canvas, Or you use GWT canvas and wrap it as an element. you need to include this dependency
<dependency>
<groupId>org.jboss.gwt.elemento</groupId>
<artifactId>elemento-widget</artifactId>
<version>${use elemento version here}</version>
</dependency>
Then you can wrap a canvas as element using this
Widgets.asElement(myGwtCanvas)
And don't forget about the inheritance of this GWT module