Pluto and USRP are almost exactly the same thing at this point, just USB2 vs USB3 so you're limited on data rates outside of the device an technically a different chip but they're an old node and binned, so they're the same in practice. You can still install an external clock into the UFL connector on the Pluto though so you can sync a few if you want or use a GPSDO for frequency accuracy. You can also install the extra Tx/Rx pair onto the UFL connectors they added recently-ish.
this should work with limesdr as well.
for something cheaper, try antsdr or adalm-pluto: https://github.com/srsran/zynq_timestamping
lots of good notes here: https://www.quantulum.co.uk/blog/private-lte-with-analog-ada...