[Android Software Development] josephcsible:
I did some more digging into the problem with the stock package. I found this getting logged when I bootlooped:

04-30 14:35:27.816 12353 12353 E System : ******************************************
04-30 14:35:27.817 12353 12353 E System : ************ Failure starting system services
04-30 14:35:27.817 12353 12353 E System : java.lang.IllegalStateException: Signature|privileged permissions not in privapp-permissions allowlist: {com.google.android.as (/system/priv-app/MatchmakerPrebuilt): android.permission.SYSTEM_CAMERA}
04-30 14:35:27.817 12353 12353 E System : at com.android.server.pm.permission.PermissionManagerService.systemReady(PermissionManagerService.java:4577)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.pm.permission.PermissionManagerService.access$800(PermissionManagerService.java:191)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.pm.permission.PermissionManagerService$PermissionManagerServiceInternalImpl.onSystemReady(PermissionManagerService.java:5051)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.pm.PackageManagerService.systemReady(PackageManagerService.java:24707)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.SystemServer.startOtherServices(SystemServer.java:2626)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.SystemServer.run(SystemServer.java:883)
04-30 14:35:27.817 12353 12353 E System : at com.android.server.SystemServer.main(SystemServer.java:614)
04-30 14:35:27.817 12353 12353 E System : at java.lang.reflect.Method.invoke(Native Method)
04-30 14:35:27.817 12353 12353 E System : at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
04-30 14:35:27.817 12353 12353 E System : at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)
04-30 14:35:27.817 12353 12353 E Zygote : System zygote died with fatal exception
04-30 14:35:27.817 12353 12353 E Zygote : java.lang.IllegalStateException: Signature|privileged permissions not in privapp-permissions allowlist: {com.google.android.as (/system/priv-app/MatchmakerPrebuilt): android.permission.SYSTEM_CAMERA}
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.pm.permission.PermissionManagerService.systemReady(PermissionManagerService.java:4577)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.pm.permission.PermissionManagerService.access$800(PermissionManagerService.java:191)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.pm.permission.PermissionManagerService$PermissionManagerServiceInternalImpl.onSystemReady(PermissionManagerService.java:5051)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.pm.PackageManagerService.systemReady(PackageManagerService.java:24707)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.SystemServer.startOtherServices(SystemServer.java:2626)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.SystemServer.run(SystemServer.java:883)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.server.SystemServer.main(SystemServer.java:614)
04-30 14:35:27.817 12353 12353 E Zygote : at java.lang.reflect.Method.invoke(Native Method)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
04-30 14:35:27.817 12353 12353 E Zygote : at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: *** FATAL EXCEPTION IN SYSTEM PROCESS: main
04-30 14:35:27.817 12353 12353 E AndroidRuntime: java.lang.IllegalStateException: Signature|privileged permissions not in privapp-permissions allowlist: {com.google.android.as (/system/priv-app/MatchmakerPrebuilt): android.permission.SYSTEM_CAMERA}
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.pm.permission.PermissionManagerService.systemReady(PermissionManagerService.java:4577)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.pm.permission.PermissionManagerService.access$800(PermissionManagerService.java:191)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.pm.permission.PermissionManagerService$PermissionManagerServiceInternalImpl.onSystemReady(PermissionManagerService.java:5051)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.pm.PackageManagerService.systemReady(PackageManagerService.java:24707)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.SystemServer.startOtherServices(SystemServer.java:2626)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.SystemServer.run(SystemServer.java:883)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.server.SystemServer.main(SystemServer.java:614)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
04-30 14:35:27.817 12353 12353 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)

When I used this .gapps-config file, then stock worked fine:

ActionsServices
PixelLauncher

I kind of want to be able to use the Pixel Launcher, though. I'm looking right now for a solution that lets me do that.

Note: If you want to try this, and you've flashed the stock package before, make sure you reinstall your ROM first to get the original launcher back, or you'll end up booting without one (if you see "Android is starting" but things like the status bar work, this is what happened).