I am trying to discover a way to disable DST on my HA installation. The system is running an HA Yellow box running HA Core. There don’t seem to be any handles in HA to disable DST, although that would be a great feature, particularly when many states in the US are considering either making DST permanent (dumb idea) or doing away with it altogether. I have to assume that HA is using the Linux system time and just follows that. If there is a command line function to disable DST in the OS that would be nice.
I’m quite sure that will take a while for them to decide.
And when that is decided there will be an update to HA.
I believe you worry too soon
HA is using UTC.
UTC have no DST.
All other times are converted from UTC.
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HA is using GMT ± N as per system/general settings. The now() function I use to make the current time sensor does update according to DST. It seems HA does not support Python datetime function which has a method for setting timezone (tz). The workaround I am using is to set the time zone in settings/system/general to a timezone further west.
Except that I am old and weird and have decided to do away with DST in my home. Changing the clock one way or the other is sillyness. It certainly hasn’t saved any daylight in my life and I challenge anyone to show me where that saved daylight is stored. 
I am not sure if there is a supported way to do this on HAOS, but I doubt it.
Is there a particular aspect of the system you care about, such that time might be adjusted to your desired flavor of local time in contexts you care about? Adjusting at the application layer might be simpler—depending on what you care about—than rigging the entire operating system to disregard the shift to/from standard time.
No, HA is using UTC.
That setting is for the conversion to your local time, when it needs to be shown in cards and the like.
If your area abandon one of the time “seasons”, then the formula for the conversion will be updated, but the internal time in HA will stay the same on UTC.