No thunder, but I've enjoyed the "white noise rain" https://mynoise.net/NoiseMachines/whiteRainNoiseGenerator.ph...
It's real rain noise - if you pay attention to it, you can hear the drops - but it's overall a nice white noise that isn't the "boring" white noise.
> ... Our recording has been performed in the silence of the night, in a huge space - namely the Harau Valley in Sumatra - and in the absence of any wind, as to produce the most even noise one can get.
Related / previous HN posts
https://rain.today https://news.ycombinator.com/item?id=9908909
https://mynoise.net https://news.ycombinator.com/item?id=32366075
Neat, bookmarked for later
I built a white noise site which has a load of sounds which can help in a similar way (including thunder): https://ambiph.one
I find the 'bass rumble' and brown noise particularly useful for masking external noise, which I guess is pretty similar to a thunderstorm frequency-wise
When I'm hearing someone else's thump thump music and my ear buds aren't sufficient to block it, that's the only thing I've found to work.