A simple replacement for firmware-selector.openwrt.org webpage

For a couple of weeks, it seems that the firmware-selector.openwrt.org webpage does not make custom builds if the Script to run on first boot (uci-defaults) field on the webpage is filled with any command.

That is a very annoying, I would like to know why this sought after feature is disabled, is there any plan to bring this feature back?

Meanwhile, I want to know if there is any similar solution (either a trusted mirror webpage or a trusted git repo) that could offer a web page or something similar like mentioned webpage firmware-selector.openwrt.org , that I can install on a Ubuntu machine and compile my custom image with some command inside the Script to run on first boot (uci-defaults)?
I would rather not to download the SDK and make menu config,.... those are too time consuming and complicated.
As I mentioned I would like not to get involved with config menus, buildroot, and complicated compile tools for the sake of preparing prepare a custom image file for a router, is there any simple alternative for that webpage available somewhere in some package or VM image.
Any hint on this issue would be very helpful, a simple tutorial with some custom firs run commands is really appreciated as well.

See The OpenWrt Firmware Selector - #684 by KSofen

See also the many outstanding GitHub issues that have been raised for this.

you can always work around this "problem" by building your custom image yourself, "offline", takes less than 2 mins to set up and build.

The normal (offline) imagebuilder is always at your disposal.

The very nature of server side -custom- image generation is fragile, as it depends on a lot of CPU power, disk space and network traffic, while at the same time being a vulnerable target to abuse/ over-usage. If the server runs out of quota, it'll be offline - if security issues are spotted, it will be offline until things are sorted, if too many users want its services at the same time, it may drop offline. If you rely on it to function at 7-nines availability, you are doing something wrong.