Not sure what you mean by bulky, but these seem pretty small to me: https://www.wimo.com/en/picoaprs https://www.wimo.com/en/picoaprs Seems pretty common to

Not sure what you mean by bulky, but these seem pretty small to me: https://www.wimo.com/en/picoaprs https://www.wimo.com/en/picoaprs Seems pretty common to put similar bare boards in people playing with high altitude balloons. Sure APRS has limits, but keep in mind that you don't have to use the "APRS" frequencies, for high density uses like say a bike/horse/foot race it's pretty common for support teams to have APRS to help coordinate and to use a non-standard frequency. So tracking 1000s of devices second by second, sure that's not going to work well.