You've answered yourself: you can't get a work permit on retirement visa. While still technically illegal, you could offer online fitness and nutrition coaching. One way to market yourself would be creating free content (reels, YouTube) - you won't make (much) money from doing that, but people who find it helpful may be interested in coaching later. (probably best to avoid Thailand-based clients though)
If you actually got a proper tourist visa (not exempt) you're unlikely to get any trouble. Having said that, yes- your long term solution is DTV. But if you're already applying for tourist visa why not just apply for DTV?
In the words of a friend: Thailand is like disneyland for men - if you have money. Philippines is more like a second rate theme park surrounded by landfills - but you can still have fun there cheaper.
What details exactly? Phone numbers is a known thing as they're cracking down on mule accounts, but other details like foreign accounts?? that does not sound right.