I would like to add to this.
I run a custom SearXNG instance on my home server using Yunohost (a reverse proxy) and would like to default to this on Vanadium.
I have checked my SearXNG settings and confirm it's on GET. I have also ran approximately 20 searches and am not seeing the option to use this as my default being populated in the Search Engine portion in Vanadium. I have tried both with and without my VPN turned off. I have tried with new tabs. I have flushed all caches and rebooted. The issue persists.
When I first login to the reverse proxy I am given an error about it being a dangerous site, but once proceeding and logging in SSL is good and the cert is verified. Could this be the issue? For reference, I tested with another known domain that is configured this way and I received the same error, so I suspect this is a Chromium security feature.
Hoping anyone can shed some light on this? I am rather frustrated.