libopenssl and openssl-util match the current turris version, so you don’t need to install those.
you should just need to install one of the openvpn-{mbedtls, nossl, openssl} packages
**if you’re installing openvpn-mbedtls, you’ll also need to install the libmbedtls package as well.
mbedtls is the new name for polarssl
In fact, if you look at the Makefile for polarssl (openwrt), you’ll see it’s actually pulling in the mbedtls source package and naming it polarssl…bizarre
https://github.com/openwrt/openwrt/blob/master/package/libs/polarssl/Makefile