You need something in between to intercept the data and it just so happens that AAWireless works for that too while it’s acting as a wireless bridge.

I have the AAWireless dongle for my car and one of the advanced options is to “remove tap restriction” to allow over 6 taps in succession. Bonus, you can convert wired AA to wireless AA.

Multi head X like this? https://www.duskopijetlovic.com/x11/unix/howto/dotfiles/2021/12/13/xorg-x11-multihead-two-separate-screens.html

if you get/have AAWireless dongle you can set it to only connect when it also connects to the radio Bluetooth.

If not You can get a toggle switch USB cable to make disconnecting easier.

Have not tried, but Sonoff has a usb switch that you can control remotely and could potentially use Google Home. https://sonoff.tech/product/diy-smart-switches/micro/

The good news is anyone can grab the GrapheneOS PDF viewer. https://github.com/GrapheneOS/PdfViewer Or from the Google Play store https://play.google.com/store/apps/details?id=app.grapheneos.pdfviewer.play

I have that exact machine in my electronics “graveyard”.

Peppermint OS was my GO-TO for speed and driver support out of the box. You can also stick in a 2GB SODIMM of ram. It will only recognize 1.5GB but still 50% more ram.

J1900 has no hardware switch. Every packet goes through CPU, so even LAN to LAN uses processing power. Add pfsense to the mix and it’s probably choking.