Can confirm, way back I wrote a small guide on how to install and configure Wireguard on the ER-X (and other EdgeRouters), and to date this article is still by far the most read one: https://merlinscholz.name/post/wireguard-on-erx/
Unfortunately 3rd party software installs are lost on updates, so you need to be local to the router before upgrading (or have a secondary VPN available).
Development of EdgeOS has really slowed down though, there hasnt been a stable firmware update in 6 months (and that was just a small hotfix).
I haven't updated/tested in awhile but last I remember I was seeing 800+ mbit/s on my dinky mips ER-X. Pretty amazing and easy to use.