Supposedly, he sells out of his phones but I haven't seen any review or unboxing videos for the Brax 3. I know that you can ask for iodeOS or Ubuntu touch.
I've watched few of his videos and they seem OK, but I would never trust a phone like that. I would suggest buy a pixel and flash Graphene OS yourself. It is best for security and privacy.
And as far as Ubuntu touch or any other Linux phone for that. They are currently so bad at security that I wouldn't daily drive them. If you want to play with them or contribute to them then that's OK but don't daily drive them.
I heard that he was a scammer or pseudo privacy expert from other comments. I wouldn't recommend that phone. If you care about the privacy or security of your device, use DivestOS with a supported Pixel/OnePlus, or GrapheneOS with a Pixel. Only buy the phone new if you are super paranoid of some zero-day vulnerability being used on you. I recommend swappa.com because they have quality control, returns, and good prices for used devices (you can even get mint quality devices).
iodeOS has been behind on security updates often (still better security against unsophisticated attacks than Ubuntu but not a good ROM): https://divestos.org/pages/patch_history
I learned about Swappa years ago and exclusively use them for buying and selling all my smartphones. I have no idea why they aren't more popular, except for the fact that repair shop resellers use it too, but they are pretty easy to avoid.
Go through Brax's videos and see if he ever shows how to do anything or if he nly talks about it but never gives instructions. There are random no name channels that show how to flash ROMs, what does Brax show?
Look at his website, does that look like it was made by someone within th past 25 years?
Apparently he has some kind of an APK file to install, how easy is it to find and what is the date of the last release?
Does he always sell out of phones, or were they never available for public buyers? Where is his ordering page? Does the order page say sold out or is there no ordering website?
My point being, add up all of the evidence and comapred it to random websites that list which used phones they sell, compare to the amount of random videos that walkthrough how to to flash a ROM, I say Brax starts to look like a con who doesn't know tech, only parrots what he reads. Compare his website to free wsbsite builders, see which looks like more recent designs and web technologies.