QGIS How to find QVariant of existing attribute

I want to add attributes, without features, that exists in one layer but not in the other using the code below. I see that I am not obtaining the "QVariant" from anywhere and just assumes it will be Double. Is there a way to obtain the correct information from the source layer? Or is there a better way of doing this?

diff = list(set(ly1.fields().names()).difference(ly2.fields().names()))
for att in diff:
    res = ly2.dataProvider().addAttributes([QgsField(att, QVariant.Double)])
    ly2.updateFields()

I have looked into using:

type = ly1.fields().field(item).typeName()

This however returns, e.g., int8. But unsure how to use it.

diff = list(set(ly1.fields().names()).difference(ly2.fields().names()))
for att in diff:
    res = ly2.dataProvider().addAttributes([
        QgsField(ly1.fields().field(att)) # Get the field from the name and make a copy you add
    ])
    ly2.updateFields()