Found the simplest solution:
- Add dashboard
template
widget to Node-RED flow - Edit properties and set
Template type
toAdded to site <head> section
- paste
<script src="https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js"></script>
into template node
It overwrites the v2.3 Chart.JS namespace and my chart displays as expected