I'm coming from the perspective that the instructions SEEM to say, somewhat clearly, that the method of 'digital signing' is to type full name.
That's here in two places (you have to click the 'I need help filling out and signing forms' thing):
https://www.canada.ca/en/immigration-refugees-citizenship/services/immigrate-canada/how-to-apply-online.html
'E-signature (also called an electronic signature): Type your full name or check a box as indicated. These are only on digital forms inside the portal.
Digital signature: Insert on PDF forms. You can type your name, use DocuSign or use secure signatures'.
Underlining is mine for emphasis.
Some forms also state explicitly that 'I agree that by typing my name, I am electronically signing my application' (see for example IMM5669e, although I can't attest to whether this is in all versions of this doc).
Now my bit of interpretation is that it seems to make sense (at least to IRCC) that when doing this, the name typed should correspond to the applicant's name, and not the name of someone who is guardian or whatever. I don't really have a better argument for this than that they seem to be saying don't put the guardian's name (and let's dispense with the 'Bob Jones /for/ [signatory]' form that is used in other contexts). They already basically accept that the person submitting is authorized to act for the applicant (caveat that one should not look for consistency).
That said: there was a long history before of IRCC returning things they don't think are signed properly even when one seems to have done exactly what they say. (Do they think the 'type your name' thing holds as acceptable only if actual submitted electronically, and they think scanning and attaching a scanned pdf is not 'electronically'? I don't know).
In the before times, I always suggested do both - type name and scan 'wet ink' signature/initial. If it were me submitting this, even now, I'd type the (applicant's) name [regardless of age] and wet-ink a vague initial [meaning not clearly identifiable letters to avoid clash with the letters of the child's name] for anything that was scanned. Necessary? Perhaps not. Belt-and-suspenders, no doubt.
And yes, where applicable, I've done this with own minor child's sig on forms.