Thank you!

They added a Zmanim API recently: https://www.hebcal.com/home/1663/zmanim-halachic-times-api

I forgot to include a link for convenience: https://www.hebcal.com/holidays/pesach

ChM1, for example, says "Torah Portion: Exodus 13:1-13:16" but the 4th aliya is Numbers 28:19-25.

Not an official Hebcal person, but I asked about this previously--see here: https://github.com/hebcal/hebcal/issues/207.  You get it if special shabbatot and rosh chodesh is turned on (major holidays also needs to be on).  You can turn everything else off to make it a fairly minimal output that doesn't require particularly extensive looping.

This link, for example, gives nothing besides candle lighting times, rosh chodesh dates, and major holiday info: 

https://www.hebcal.com/hebcal?v=1&cfg=json&maj=on&min=off&mod=off&ss=on&s=off&nx=on&mf=off&start=2021-03-20&end=2021-04-15&c=on&geo=city&city=GB-London&lg=sh&b=18

Which is more than just Shabbat times + molad, but not by a ton, and the other stuff is things you'd probably be putting in a shul email anyway (at least shul emails I've seen).

Not sure if this should be a new topic, but the issue still seems to exist with havdalah times.  For example, this coming Shabbat (Beshallach 5781) with the ZIP code 10023, Hebcal shows a havdalah time of 5:52PM.  Myzmanim shows 5:55pm (really, 5:54:17).  This sun-position-calculator https://www.sunearthtools.com/dp/tools/pos_sun.php?lang=en shows that at 5:52 the sun is only at 8.1 degrees at 5:52pm, and is at 8.5 degrees between 5:54 and 5:55pm.  The Python zmanim library (https://pypi.org/project/zmanim/) has it at about 5:55 too (5:54:48, later than myzmanim by about 30 seconds, which could just be slightly different locations for 10023 vs my lat/lon).