I was in the same situation on Windows, and I prefer free open-source when possible, but it's pretty bare on the video editing front. I saw
this opensource.com review which suggested that Bender was the best of a poor set of choices. I'm old and couldn't be arsed to figure that out, so I ended up getting an Adobe CC license, but apparently that's not a native option on Linux. You may want to think about running a VM.
For recording, I use Open Broadcasting Software (OBS), which is free, multiplatform and excellent. Make sure you uninstall all codecs/codec packs first, and properly install
ffdshow (skip the outdated manual filter install and get MPC-HC directly) and ffmpeg. You should be installing ffdshow tryouts (a fork), not plain ffdshow (dead).
If you have an Intel processor and a motherboard with QuickSync support, you can enable it in the BIOS and set up a fake (or real) dual monitor, then set OBS to record on QuickSync. This lets your otherwise unused integrated Intel graphics handle the recording while your regular graphics handle the gaming--it's the only way I can record 1080p/60fps without substantial performance loss and dropped frames. I'm not sure if QuickSync is supported on Linux, but I don't see why not.