I actually do this.
you can just run luma directly using ntrboot method, thus giving you a temporary access to cfw.
with that all you need to do is run homebrew launcher amd run freeshop on it
I tested this with themes, all I did is install the tickets and cancel the download, I also qued up one game to download on sleep mode.
reboot the console without ntrboot, thus loosing the cfw.
I can now download all themes on theme store, also the game is downloading, and it does work playable and can be updated without worries, there's also happens to eshop with circle on the icon, if you run it, all those thing you downloaded over freeshop are automagically deleted, so dont run it.