If a non-profit receives donations to pay developers, is there an 'intention to monetise'?

No. Whether a non-profit uses donations to pay developers or for other purposes is irrelevant to determining whether there is an intention to monetise.

The CRA explicitly states that "the development of products with digital elements qualifying as free and open-source software by not-for-profit organisations should not be considered to be a commercial activity provided that the organisation is set up in such a way that ensures that all earnings after costs are used to achieve not-for-profit objectives" (Recital 18).

Furthermore, "the mere circumstances under which the product with digital elements has been developed, or how the development has been financed, should therefore not be taken into account when determining the commercial or non-commercial nature of that activity" (Recital 18).

For more on how intention to monetise is assessed, see What does 'intention to monetise' mean under the CRA?.