Gigabit throughput for WireGuard is, from what I've tested, only available with x86_64/AMD64 with AES-NI. (Note: I have not tested "mvebu" devices yet.)
WireGuard is available in packages, as is a LuCI interface for it.
802.11s is supported with wpad-mesh and it may be that wpad-full on master supports it as well. IBSS is generally supported. Check the wireless driver, especially if not a QCA chip set, however. I believe the Marvell wireless does not support 802.11s and haven't looked into IBSS.
batman-adv and OSLR are available through packages as well. It comes down to a choice of the technology and routing you prefer.