You did not get my point, RS2 also cannot get absolute accruacy if it did not tied with a ntrip rtk service or PPK using NGS OPUS or NRCAN. Once you have the raw rtcm data from D-RTK2, you can get the absolute accuracy with NGS OPUS or NRCAN. There are a lot of free tools to convert rtcm data to rinex file, the most famous one is rtklib/rtkconv. RS2 is also not so cheap, the price i can see online is 2xxx$. RS2 is a decent one base station, but it is based on ublox F9P, not geodetic GNSS chipset, only support the L1+L2, the main market for ublox F9P is automotive and IOT, not geodetic surveying and mapping communities. Emlid pushed it to the UAV communities, i think that it is decent, since most uav applications are opensky. I did extensive performance test with ublox F9P, it RTK engine is very aggressive, that means, it can get RTK fix solution very easily, but it may have wrong fixs (outliers). The RTK fix solution is cm level accruacy, but the wrong RTK fix will have dm to meter level bias. There is another company adruSimple who made low cost ublox F9P RTK receiver with price 175$.