Thanks for the response Alca,
I ended up trying to re-generate a cert and took the following steps:
sudo ./generate_local_ssh.sh
sudo cp testing.crt /usr/local/share/ca-certificates/
sudo ca-update-certificates
>> Updating certificates in /etc/ssl/certs...
>> 1 added, 1 removed; done.
>> Running hooks in /etc/ca-certificates/update.d...
>> Replacing debian:testing.pem
>> Removing debian:testing.pem
>> done.
>> done.
I then verified the certificate was added, then when I visit https://localhost:8080/viewer.html I get
NET::ERR_CERT_AUTHORITY_INVALID
Subject: localhost
Issuer: localhost
Expires on: Jun 27, 2020
Current date: Sep 30, 2017
PEM encoded chain:
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
Edit: I should mention that on twitch, I get net::ERR_INSECURE_RESPONSE instead, and it seems to fail to process the GET.