Alright, let me explain my dilemma:
So I figured out a way to write PNG data to my NFC card using an app called "NFC Tools" (package name is com.wakdev.wdnfc) and Termux. I used Termux to copy the raw PNG data to my clipboard, then pasted it in the app, and set the data type to image/png. (Note the image size is a mere 265 bytes, being a 1-bit colormap at a resolution of 64x64, while the card can carry up to 1KB.) It wrote to the card without issue, but when I tried to read it, I got moved to a window named "New tag collected", and below it read "image/png". Now, I believe it has something to do with the Nfc Service itself, probably a lack of an implementation. I can understand why they'd leave it out, I mean, come on - who's going to be doing this regularly? Anyhow, I would really appreciate help with this, thank you in advance!
So Android's NFC service looks for an App that has registered to receive this type of mime Type from NFC (Lots of the more NFC Forum standard ones are handled by the web browser, system settings App, email client, etc) but putting an image on a NFC is very rare, so the system NFC App has a fallback popup message that just describes the card in text format the best it can.
You can write your own app and register the "image/png" and it should start that. See the docs on how to do that.