If you’re using a spreadsheet to design your form:
type
select_one [list name] or select_multiple [list name] ... depending on how many things users have to consent to ... with those things listed in the choices tab
You could pace a 'Do you Consent?' Q (with a 'select_one' option), coupled with a second question capturing signature (per the suggested method from @Vanubhav) on the same page/screen. This can done by placing these 2 questions in the same group and placing 'field-list' in the appearance of the group.
A potential issue using field list in this example is having the signature contingent on the 'Do you consent' Q (if they are on the same page, relevant statments can't apply), so signature would a) not need to be required or b) be captured even if they do not consent.
Currently, no, you can't have fingerprints in the form. You'd have to have a device that does fingerprint scanning and add Java code to Collect to support that. If this is feature you'd like, file it at https://forum.getodk.org/c/features.
One alternative you might want to consider is the signature widget. You can add that today, but note that increases the size of your submission because it's a picture.