It is possible to transmit AM with the LimeSDR-USB in the 1 MHz region - evidence of that is shown in my post on that (awhile ago) here:
At 160m (1.825 MHz) the output of the LimeSDR-USB is -8.77 dBm. Admittedly this isn’t a lot of power, but if you design or buy and then apply the right post-amplification in place you’ll be able to put the signal out at any level you want. Now this measurement was made in the 160m Ham Band, but it is very possible to re-tune the LimeSDR-USB to 1.0 MHz (or wherever you want to tune to) and transmit there with similar power output from the LimeSDR-USB and whatever post-amplification you provide at your frequency of interest.
Hope this helps - 73 de Marty, KN0CK
So the answer is: Yes, but the effort to get it to the power output level