Thanks for the feedback.
Not sure how exactly to interpret the below but below is what I get back as the "Issuer" information from my certificate. COMODO Certification Authority seems to be trusted based on the list in the link you provided.
CN = COMODO RSA Domain Validation Secure Server CA
O = COMODO CA Limited
L = Salford
S = Greater Manchester
C = GB
In regards to the openssl changes, they are quite extensive (4 years) worth, and I am not sure I can quite pick out what change may have had an adverse effect, although I did go through their CHANGES file.
Wouldn't the fact that I can replicate the issue outside of Pythonista "prove" that this is not specific to iOS but specific to the openssl version used by it?