Carbon14 In my organization, GrapheneOS would be welcomed but the lack of voice recording is a no-go for now.
Depending on the size of your organization, it might have an IT person who could do custom builds of GrapheneOS including BCR (or something else). The build directions are clear enough that even I was able to do it, despite never having written any Android code at all. Arguably the build directions could be improved by adding an explicit list of the steps necessary to re-badge the resulting OS (i.e., so it doesn't advertise itself as "GrapheneOS", uses a different boot logo, etc.). A "private label" OS for your organization could probably be deployed in a week or two (including an update server).
At the other end of the timeline spectrum, contributing call recording to Google's AOSP project, if successful, would likely result in it showing up downstream in GrapheneOS. That could easily take more than a year -- again, if successful: Google might just not be interested in adding call recording to AOSP. I suspect they would not at all want to incorporate GPLv3 code such as BCR or any derived work (which would also be GPLv3).
Please note that I don't in any way speak for the GrapheneOS project (and certainly not for Google!).