The XBee can be used without a processor and has a few ADC inputs (see the data sheet).
For point-to-point the Series 1 XBees running 802.15.4 are recommended. These do require a Vref applied but this can be the 3.3V used to power the XBee. The ADC data can be gotten out of the ‘other’ XBee by either setting up a sampling time and it sends or query for data from the ‘other’ XBee.
There are many threads here in this forum with discussions about this. So go through the threads and read.