If you're looking for a prebuilt "no tinkering" solution https://diffusionbee.com/ is an open source app (Github link at the bottom of the page if you want to see the code) which has a built in button to import Flux models at the bottom of the home screen.
I usually don't want to comment on these, but: DiffusionBee's repo https://github.com/divamgupta/diffusionbee-stable-diffusion-... don't have any updates for 9 months except regular binary releases. There is no source code available for their recent builds. I think it is a bit unfair to say it is open-source app at this point given you are using a binary probably far different from the repo.
