Using AirVPN in Firefox (like private mode) w/ extensions?

[Qen'Liar: Daemon Veritatis 0]

Hey, all!
I love AirVPN, and I regularly use it for filesharing and sometimes my phone.
For the most part, I find it too annoying to use it as my primary driver on my web browser (Firefox), due to my closest server being in a dif. country, and this causing lots of headaches.

However, I'd like to set it up in FF so that ALL private mode traffic goes through a kill-switched AirVPN / OpenVPN connection.
Could somebody explain how I might do this? Lots of googling today, and I haven't found a definite or current solution to this.

I run Pop!_OS 22.04 (Linux->Ubuntu derivative) and the current, updated Firefox.
Thanks!

[OpenSourcerer 1435]

Uhm, AirVPN is a VPN provider, not a proxy provider, so the use of addons is out. OpenVPN/Wireguard used by AirVPN operate on the IP layer, so either all or nothing is going through the VPN connection. Exceptions can be configured but is rather technical.
I believe that a separation between regular and private windows cannot be made since all browsers today are using a main process starting different worker processes for sandboxing purposes. It's in their nature to not being really "fixed", or "predictable".

[Qen'Liar: Daemon Veritatis 0]

I must have gotten confused with QubesOS, which def has support for certain containers using different VPNs, such as Whonix dist, for certain and independent tasks.
I've been playing around with always-on VPN on my PC, and I've noticed a def. slowdown in my normal traffic and higher latency.
Anyway -- thanks for the reply!