There is no formal system for that.
If we had a system like that then any user could put anything into it and there would be no way to know what was secure and what not. What is being asked for is a file sharing system with pre-built images of iso’s. Without the full availability of the git repo behind it and all the lfs files etc to show how the image/iso was built, there would be nothing to be able to confirm that what was being provided for other users to download actually was a build of a normal IPFire, without any malware or other unwanted content.
Rather than having several users doing builds of IPFire for RPi5 and each talking about different ways of modifying or editing the IPFire build it would seem to me to be better to be having the discussion about who is willing to step forward and take up the suggestion provided by @ms earlier in this thread.
Then the work to define and submit the required drivers etc into the IPFire build would mean that all RPi5 users would be able to access the result and any user could verify the result by looking at the files used to build the image/iso and even build it themselves to confirm that what is being provided has been built from the git repo source.
Unfortunately, so far there has been no comment or interest shown in following that option.
Note that the version being shown is behind the current Testing Release. It refers to 9b7ed567 while the latest CU203 Testing is 4b639c7e (with 10 additional commits) and sometime fairly soon CU203 will no longer be a development build but a released version.