The one they ended up using was TP-Link Deco X50-5G, but honestly I'm not sure if I can fully recommend that. It has had its own share of problems...
replyI recommend Glinet's mobile routers: https://www.gl-inet.com/products/
replyI have several of them in a cross Atlantic Wireguard mesh, and they are bulletproof.
I actually use the non-mobile Flint 2 myself at home, and it's one of the devices in my tailnet. I worked with their engineers on the forums to get better IPv6 support for their WireGuard tunnels. Running both Tailscale and WireGuard on it can mess up the routing at times though, so I prefer to stick to just either or.
replyIt's a bit unfortunate they decided to go with Broadcom for their Flint 3 router, since Broadcom is known to not play well with open source. One of the reasons I got Flint 2 was its Mediatek chip, since stock OpenWRT support for that should get reasonably good eventually. They're all still way more open than TP-Link Decos.