What's the best way to use this data?

[tecnobabble]

I'm using ics.py and went way far down the rabbit hole with converting times to UTC to be consistent, only to discover that breaks RRULE reoccurrence in fascinating ways (dateutil/dateutil#827 (comment)); the correct way to implement this seems to be to implement VTIMEZONES in the file, but how do I dynamically include these wondrous ones listed here in my generated .ics files?

[N-Coder]

I'm using ics.py and went way far down the rabbit hole with converting times to UTC to be consistent

Seems exactly like the way I ended up here when I found out that ics.py has a few issues with handling files in a standard-compliant way. 😅
The code here is part of a larger series of PRs to fix all these issues and produce a revamped version 0.8 of ics.py, see here.
The specific PR requiring this repo is 249 and some more of the rationale why this data resides in a separate repo is explained here.
The PR is ready to be merged, unfortunately that is waiting for C4ptainCrunch, who is the only one with full rights to the repo but is probably currently caught up with his thesis.
With 0.8, converting timezones of Events should be easy to do, with the necessary data from this repo being factored in invisibly in the background.
With 0.7, this unfortunately is pretty hard, as even trying to parse this data into a Calendar wouldn't yield any useful results.
If you need a quick fix, parse the required timezone files into ContentLines and prepend them to the items in the Container your Calendar got serialized to - or simply put them into the extras of your Calendar, that might already suffice.
If you're also eager to get a proper solution for this, maybe have a look at the issues I linked and feel free to get in contact with me if you want to help out there.
I'd be pretty happy if I were no longer the only one to work on the code of ics.py.