This solution contains a PCF control for displaying an informational message on a Model Driven App form
This PCF control was created to solve a limitation on quick create forms, where an information message could not be displayed inline on a quick create form. This PCF control solves that by binding to a multi line string field which should be set to the html for rendering in the message
The solution for this PCF control can be found here, and the code repository here
This screenshot shows a field Custom Message field configured to use the PCF control

For the purposes of an example message this Business Rule triggers on account forms to populate the HTML into the Custom Message field. Note this gives the flexibility to display contextual messages with relevant field information

This screenshot shows the PCF control displaying a message on the quick create form. As you can see this gives extra flexibility in displaying information to the user than standard configurations

If you have any questions on the implementation or use of this PCF control feel free to comment