How can I tunnel VPN through 2 exit nodes?

[SecureGate]

I have configured two Wireguard VPNs with this manual. However, I want my VPN to be set up like this:

Client → WARP (automated colocation) → ProtonVPN (Japan)

• The client should connected through WARP
• The WARP VPN should be connected through ProtonVPN first, so the colocation will be Japan instead of the nearest one.

I have tried this concept using OpenVPN (ProtonVPN) and Wireguard (WARP). I could connect to Japan using WARP, which is tunnelled through ProtonVPN, but I was confused about configuring this on OPNsense.

PS. I also posted this question on Reddit.