Currently, kernel 5.4 is a bit challenging to compile for the device due to it's uboot web limitations to a 2MB kernel size.
I've created a thread talking about it: https://forum.openwrt.org/t/gl-inet-ar750s-nor-nand-not-producing-the-factory-image/73518/4
As a result of compilation issues, I have switched source code and preferred passwall/smartDNS over ssr-plus as a reference to #3
When the new kernel issue is resolved, I will try to compile and release a more easy to use configuration file.