Consider whether you want just Chinese numerals, or also Arabic (normal) numerals in the corner.
Consider which style of mahjong it will be used for. Depending on the style, there are different numbers of total tiles included in the set.
The feel of the tiles might matter to you, but unfortunately that may be difficult to judge when buying online.
You know damn well this isn’t about surgery. It’s about hormones, and it says so right there in the summary. You didn’t even have to click the link. Nobody is doing breast implants on trans minors (only on cis minors, which is perfectly fine for some reason).
Forcing a trans kid to go through the wrong puberty even though they know they are trans is extremely traumatic. It’s life ruining. It alters the voice, the shape of the torso, the shape of the face, and facial and body hair in ways that either can’t be fixed at all, or can only be fixed with expensive surgeries later on.
And if you want people to be absolutely sure about their status before going on hormone replacement therapy, then that is exactly what puberty blockers are for. Leuprorelin prevents puberty so that the kid can figure themself out for a year or two, and then make sure they go through the correct puberty. Even if they decide not to be transgender in the end, they can just go off leuprorelin and start puberty.