Calendar proxy? - Public calendar for Humhub with Baikal

I have the following requirements:

• LAMP server (Humhub and Baikal already installed)
• I need a public calendar that I can integrate into Humhub (via the "External Calendar" plugin in HumHub)
• this calendar will be populated by a few people, who need write access
• for integrating it into HumHub it should be made availible only with read access.
• Setup only with open source tools, as minimal as possible, which is why I installed Baïkal as calendar service (I know that my problem would be solvable with OwnCloud/Nextcloud)

Now I noticed that there is no option to make a calendar in Baikal publicly available. With some research I found an existing issue in Baikal.

https://github.com/sabre-io/Baikal/issues/1039

Out of curiosity (and to keep me from surrendering and installing Nextcloud), is there a possibility to cheat my way around this?

My plan would be the following:

1. New Baikal user that can only read the calendar
2. Set up some sort of proxy, that uses the read-only account to fetch the calendar data to the server and offer it back to HumHub without authentication via an URL

I tried to find an existing solution like this online, but I guess I am not using the right keywords. If someone has an idea, I would be quite thankful!