Hi! So, let’s split your potential ideas by what implant would be best.
For all of these, the NExT would work very well. The NExT contains both an HF and LF chip (high frequency and low frequency). The LF chip, the T5577, can have many common building key cards cloned/copied to it.
The HF chip, the NTAG216, can have something called an NDEF record written to it, which can contain a ton of things (website link, wifi password, even an address). This is what phones will read when you tap a chip to them.
You mentioned contact sharing, which the NExT can do, but only on Android. This is done using something called a vCard, and only Android phones can read them from an NFC tag. iPhones can read a website link though, and you can always write a link to a website containing your contact info. However, due to the low Apple market share in Brazil, this might not be an issue at all.
The VivoKey Spark 2, (which you’re calling the vivokey 2), is a neat chip, but it isn’t super useful for most of the things you want to do. The primary use of the Spark 2 is proof of identity, which can be used for a few different websites (including this forum). You can also have it redirect to a site of your choosing when it’s scanned. It doesn’t have an LF chip, and can only be used for a limited amount of door locks, specifically locks that you can enroll yourself in (something like an apartment). It wouldn’t be good for a school, hotel, etc.
The only chip for this would be the Vivokey Apex, specifically the Apex Flex, which is still unreleased (but coming very soon), However, the Apex Flex is a much bigger implant, and would be very difficult to convince your parents to get it. You also need someone in your area to be specialized to install it.
This is a very tricky area. I would read this:
Essentially, unless there’s a payment provider in Brazil that provides mini-cards that could be turned into an implant, there’s no real option here. The Apex can theoretically do payments, but it still needs regulatory approval, which might never happen.
Honestly, I would probably just wait until you’re 18. The argument is much stronger at that point, and you probably won’t have issues convincing them. I’m close to your age, I just turned 21. I got mine when I was 19, and it was super easy.