I created a tool over the weekend to guess the f-string you seek: http://pym.dev/format

I'm also the author of https://fstring.help/cheat/ (though not of the homepage) and I haven't yet linked back to that new tool. I was surprised to the cheat sheet here today but not the format guesser.

Is it at all possible to use spaces as the thousands separator in Python f strings?

At the very least, your tool wasn't able to figure it out and hardcoded most of the number I wrote in.