Doing a $10 UTXO would not be smart. Will more than likely become dust or will cost on a 1-2% on-chain fee to move it.
Discussion
$10 on-chain will force them not to move and take action and learn. On a sat card 10 bucks im sending that to cashapp and selling for 2 donuts hahahahahaa fees go high now they really have to study hahaha
If you run a node you could make LNURLw links so that the funds are only moved off your node once the user takes the learning action. Plus since it’s lightning (on your own node) you don’t need to trust anyone.
If you want to try out an LNURLw you can test run http://lightning.btcforplebs.com
The LNURLw links are printable qr codes and easily written to NFC tags
You also remove the fees involved with on-chain