Managed to find a workaround of sorts.
Flywheel suggests (https://localwp.com/help-docs/ssl/managing-local-sites-ssl-certificate-in-macos/) to edit your keychain for the local site, they advise double clicking the site certificate within keychain access and changing “When using this certificate” from “Use System Defaults” to “Always Trust”.
However, doing this does not resolve the issue with Google Chrome. Nor do any of the other steps presented in the guide.
The only way I have found to access a site that I’ve pulled to local app that is secured with SSL, it to go to Keychain Access for the local certificate for that site (Search your-domain.local) and instead of double clicking, right click and choose “Evaluate…”.
Then tick the SSL radio button, and “Ask host for certificate” checkbox, then paste the full local site url into the Host Name field. And click continue.
If you’ve followed Flywheel’s advise and changed “When using this certificate” from “Use System Defaults” to “Always Trust”. Change it back, or it won’t work.
This will now provide the link within Google Chrome to “Continue anyway”
It’s not ideal, but at least you can access your site in Chrome now.
(For full disclosure - I had followed all steps of the Flywheel solution which didn’t work, so it may be necessary to follow the BASH command to force HTTPS, but I suspect not, so have left this out from this workaround)
Hope this helps someone else who’s been struggling like I have - support were useless, just sending me to this forum where there was no solution!