I think the problem is that you will hear a lot of rules of thumb, but none of them are really targeted toward the Mustachian audience. E.g., mortgage lenders will allow you to borrow up to a total debt load of 41% -- but how the hell is anyone supposed to save anything if 40% of what you bring in is flowing right back out? I have also heard home value up to 3X income, but wouldn't the reasonableness of that figure depend on how cheap/expensive mortgage rates are, what other costs you have, and whether you live in a LCOL or HCOL?
Personally, I would look at it in the context of your monthly cash flow, based on a 30-year mortgage with the standard 20% down, if you can swing it. How much do you want/need to save for your FIRE target? How much are your other expenses? So how much does that leave that you can afford for a mortgage, without sacrificing other things that you value? Remember to include not just PITI, but increased utility bills and a maintenance fund. Once you figure out a monthly payment, you can figure out how much house that will buy you, and start looking around to see if that will get you something that you would be happy/comfortable living in.
And then, if you're like most people, your first crack at it will be depressingly horrible, and you will want to look at higher-priced homes. :-) That's ok, too -- but what is going to give? Are you willing to deal with a multi-plex or basement rental to bring in extra income to offset the difference? Are you willing to save less toward FIRE to get a nicer house? Are you willing to work more OT/side hustle to increase your income to the kind of house you want, or move to a LCOL area? Etc.
Tl;dr: Don't go by generic rules, because those rules do not have your specific best interests at heart. Figure out the sweet spot where what you are comfortable paying intersects with a place you would be happy to live in. And if those two don't intersect at all, keep saving/increasing your earning potential until they do.