Your points are all accurate and have been made before. LE can’t just sneak an ankle bracelet onto a person hush-hush. The procedure is entailed, as you described.
Also, while bell-bottoms could conceal an ankle bracelet, those gray support-boots couldn’t. The ankle bracelet is bulky, and would make even fastening those boots a challenge. If successful, the boot would bulge way out on one side. It’s obvious from the pics that this isn’t the case.
It would certainly be possible to build an ankle bracelet into a boot. Not saying this has been done, but certainly it’s possible.
I also think it’s possible to build a much less bulky ankle bracelet. Until this recent crop of celebrity criminals, there was no reason to try to accommodate a criminal with a non-bulky monitor. (IMO there still isn’t, but maybe the plan involves not making their indictments public yet, so they can round up more of the co-conspirators.)