I still put the important part of my network behind my own router similar to yours (and in terms of security I think ubuntu server + whatever you need has likely much smaller attack surface than OpenWRT which is a piece of software just too tasty not to be exploited).
Outside that, wifi part is hard to get right and smart switches are nice to have, but they are PITA if the firmware is never updated and there's no single place to nicely manage it all.
Can you expand on the security of an Ubuntu server (acting as firewall, router and vpn), versus a dedicated router hardware and software (eg pfsense or OpenWRT)?
I'm having already Unifi's AP's, the controller running in my NAS and a good switch for the current setup.
Do you have some better suggestions for the router software? I'd love to run Opnsense, but a native Wireguard client is a must, and so is a good web interface for the setup.
Outside that, wifi part is hard to get right and smart switches are nice to have, but they are PITA if the firmware is never updated and there's no single place to nicely manage it all.