Probably not total bullshit, but I don't think we know enough to say for sure what the best fasting/eating schedule is for everyone.
I've head this guy: https://www.salk.edu/scientist/satchidananda-panda/ on a couple of podcasts, and he seems to be the expert on food and circadian rhythms, so you might want to check out his book. https://www.amazon.com/dp/B07BVF1Z6Z/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
I'm reading 'The Circadian Code' by Satchin Panda, who is a leading expert in the field of circadian rhythm research. He talks about how he wore a special light tracker on a working vacation in Kenya, and also at home in San Diego. In Kenya, working outdoors, mostly in the shade, he got 8 hours of moderate to bright light daily and slept much better. At home in "sunny San Diego" it turned out that "my light readings during the weekdays were miserable [because he worked indoors], I was hardly getting an hour of bright light" per day.
While the device he used is not yet commercially available, he writes that one of his students developed a free app to measure light brightness, which is only available for the iPhone (I have Android, so I haven't tried it);
https://apps.apple.com/us/app/myluxrecorder/id1069557831
Even very outdoorsy kids in the USA will have spent 9 months of the year mostly indoors. And most of us are indoors most of the time year-round as adults. Indoor lighting doesn't come anywhere close to peak, midday sunlight, as Panda's example shows. Even therapy lamps are typically only 10,000 lux, while peak sunlight can be 100,000- 120,000 lux.
I've used a 10,000-lux therapy lamp myself and had no effect from it, but - like you - I do notice some effect from sunlight. Plus, it feels great and helps my mood.
FYI - try the free, doctor-developed D-Minder app to help get your Vitamin D. It will tell you what hours you can make Vitamin D on a given day in a given location, how long you need to (and can safely) stay outside, etc. I'm at approx. NYC latitude and I was pleased to learn that late last summer/early fall I was still in the Vitamin D window as late as 2:30- 3PM. Since I was waking up at noon, that was a big help. Even if you're taking supplements, it still helps to get some D via your skin when you can.
You can get a 10,000-lux therapy lamp pretty cheaply on Amazon - I think mine cost $40 - so it's worth experimenting with one if you can afford it. Everybody is different and some people do respond to them.