Earlier quoted context omitted.
Why Juniper? I would not trust proprietary stuff over Strongswan, even if it worked correctly :) And Apple IKEv2 native clients work fine too.
strongSwan is literally 2 orders of magnitude more code than WireGuard, and for all that you get 1990s cryptography. Why would you trust it at all?
Codebase size is good argument, but consider how many optional components are in Strongswan, tens of RFCs supported. You can build it smaller omitting it in make.
And what is the size of OpenBSD iked?