For backtest of a proorder code, in terms of drawings you can use graph and graphonprice commands, to display values taken by variables of your choice. Graph output goes in a separate window pane, graphonprice output goes in the price window. It will appear as lines, you can work on their names and colors. Mainly useful for debugging purposes. But beyond that, you can’t do all the drawarrow, drawtext, or any of the drawXXX commands available for indicators only.
https://www.prorealcode.com/documentation/graph/
https://www.prorealcode.com/documentation/graphonprice/