You could always manually edit the settings.db to use a password that has characters not included in the entry screen. I've done this myself as proof of concept so I know it works.
The Wifi SSID and password are held in clear text in the 252 byte binary blob WLAN_CONNECTED_AP in table "TBL_MENUCONFIG"
The SSID is at offset 0x00 and password at offset 0x78. I think it could definitely be do-able to create a webif page to display or modify all the current network settings, not just WiFi.
Here's a couple of screenshots showing the WiFi settings blob "WLAN_CONNECTED_AP", and the IP address blob "ETHERNET_CONF_1ST_IP" which holds the 4 byte hex value of the current IP address.
Obviously, I have edited out my real network SSID and password.
View attachment 1531View attachment 1532
I've started work on a web interface screen to allow setting network parameters but won't have much time today to continue.
The settings need to be applied during boot so I'm writing a generic boot-time configuration update package. If there are other settings that would make sense to expose in the web interface then it will be fairly easy once this is in place. There may be little point since the settings are rarely adjusted and almost all available via the standard on-TV menu in any case.