100 Mbps is nothing for such a SoC I'd reckon. You should do some tests with WireGuard set up on your router. This topic should give you an idea of what's possible:
Overview
While there's been a lot of individuals testing various routers, the question still always seems to come up, "What can I expect from Router X?"
I won't say that my testing is going to definitively answer those questions, but at least it should be a self-consistent data set.
To be very clear, this is a benchmark. Like most benchmarks, the performance you get in your own environment may be different. If you have a craptastic ISP, a lossy ISP connection, a flakey cable, hosts pummeling y…