Or just, you know, use a high frequency. There are tiny antennas. You can just power it via induction (like RFID) and you're set. It still couldn't transmit super far but I bet it would work.
This isn’t true in any sense applicable to this discussion. For example a near-optical laser transmitter can be as or more efficient in joules per bit than an RF transmitter, depending on the situation.
Do you have to aim that laser transmitter?
* you have more options than with RF (optics or phased array)
* you’ll get better angular precision at a given transmitter size
"Also, new results that give insights into power efficient beam steering algorithms".
From "Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond"
Also, plans are to use directed energy, not classical wave like RF.