do you have the case on your proxmark? if not you should be putting it on. the case acts as an often necessary obstruction to prevent “too good” coupling which sounds counterintuitive because it is.
magicrevive just runs manually block sets and a wipe, cwipe will do it for you.
due to the small antenna size of implants part of having on is finding the sweet spot in which to hold your proxmark to get a good write, this takes time and experience but eventually youlll get there.
as for the LF portion, while you can buy the implant antenna my personal experience of having one & another custom made one honestly just flipping the antenna out like so and putting the implant underneath (so not on the antenna side, underneath in this context would be the ‘top’ side of the antenna) to get decent coupling.