I use the GL.inet Shadow and have been happy with it. If you want 5Ghz and don’t mind that it’s a little larger (still small), I’d consider the Slate. It supports the latest version of OpenWRT. https://openwrt.org/toh/gl.inet/gl-ar750s
They include a custom GUI on top of OpenWRT, which I like. But LuCI is still there.
I’m not sure about all your requirements. I use 1CRM. It’s based on sugar crm, which is open source. It’s self-host-able. I had a good experience with support while I was setting it up (I pay for hosting). They are located on the west coast of Canada, if time zone matters.