I'm currently using Oxford Oberon-2 compiler but it doesn't seem to support the XYplane module, which makes it kind of difficult to follow the examples from Wirth's book about the language.
Unless you need type-bound procedures, you could try OBNC which implements Niklaus Wirth's revision of the original Oberon language:
https://www.miasap.se/obnc/oberon-report.html
See also