This doesn't seem to be supported by the official project...
But this one is...
https://firmware-selector.openwrt.org/?version=SNAPSHOT&target=qualcommax%2Fipq807x&id=spectrum_sax1v1k
There also appears to be some information to suggest that the RT5010W is a rebranded DL-WRX36 based on this thread.
I'd recommend installing the sysupgrade image for the SAX1VK as linked above.