In addition to this https://forum.openwrt.org/t/strongswan-dependency-on-xfrm-and-gmpdh
I believe strongswan-mod-wolfssl is broken because of wolfSSL version mismatch (tested on 23.05.0-rc3).
I get:
plugin 'wolfssl' failed to load: Error relocating /usr/lib/ipsec/plugins/libstrongswan-wolfssl.so: wolfssl_ec_diffie_hellman_create: symbol not found