Partitions offer no security in any context. It sounds like what you want to set up is a VM. Also, free VPNs are a little sketchy, (a browser extension even more so) and kind of eliminate the point of airvpn. Windscribe is not terribly trustworthy-- On July 8, 2021, Windscribe disclosed that two VPN servers hosted in Ukraine were seized by local authorities on June 24, 2021. On the disk of the VPN servers contained an OpenVPN private key, which could have been used to impersonate a Windscribe VPN server and capture traffic running through it. Windscribe had failed to encrypt the servers in question, allowing for the retrieval of the private key. In addition, Windscribe ran servers with an OpenVPN feature that was deprecated since 2018, leaving the servers unencrypted and its users vulnerable
--the only free VPN I'd trust is Proton, as it is a nonprofit with a clear mission. https://www.virtualbox.org/manual/UserManual.html#virt-why-useful
Virtualbox is a popular one, and can be installed from the Linux software manager of your choice.