Looking for a budget quadcopter FC

Hello everyone.
I own a race quadcopter since a month, and my dad loves watching me fly it. He hopes he’ll have one soon too so he can fly with me.

His birthday is at the end of the month, and I’m willing to help him build his own quadcopter like I did.
I have a Mamba Stack Basic F405 MK3 with 4 BLHeli S ESCs.

I also want to get him a FC stacked with ESCs, but unfortunately the one I have is out of stock until the end of the month, which means I’ll not have it at home anytime soon.

Do you know any FC that doesn’t have any Ardupilot Firmware limitations, and has stacked ESCs ?

Thanks a lot

If you’re comfortable with rewiring a FC-ESC wiring harness, any BLHeli 20x20 ESC will in theory work with the ‘mini’ boards here: Autopilot Hardware Options — Copter documentation
The cheapest easily available 20x20 FCs that work are probably the Mamba F405 Minis, not officially supported but some people have had success - see this thread: Diatone fc firmware - #12 by Lorenz_Fischer