OH2 to OH3 openHabian: No valid OpenPGP data found

I have found;

Effects of the sunset of Bintray - #39 by dastrix80 which is a long confusing set of exchanges, some of which seem to apply to openHabian and others which may or may not.

openHAB 2.5.x and the sunset of Bintray which recommends either doing some things to continue using 2.5 or just upgrade to OH3, the latter of which I am trying to do.

I also found a second set of instructions on how to upgrade openHabian 2.x to 3.x, and it gives very different procedure;

which is very involved and not entirely clear to me.

In one of posts noted above, you answered a question about manually removing the Bintray link with “openHABian now should offer to do that for you on start.”

openHabian config script does not do that for me. So I performed the following;

wget -qO - 'https://openhab.jfrog.io/artifactory/api/gpg/key/public' | sudo apt-key add -
sudo apt-get install apt-transport-https
echo 'deb https://openhab.jfrog.io/artifactory/openhab-linuxpkg stable main' | sudo tee /etc/apt/sources.list.d/openhab.list

I also removed Bintray from the list above.

Each time I make a change, I reboot and execute 01 and 02, to ensure all updates in those areas are performed before trying 03.

The openHabian-config file version seems stuck on Version 1.5-541, and has menu options that don’t appear in alignment with a number of recommended actions, e.g., openHAB release is menu item 41, not 42.

This last time around, the original problem is not solved and the rabbit hole appears to have grown into a subterranean cavern (at least for my skills).

I have 20 devices or so and a rather uncomplicated openHabian configuration currently, and I have backed up my current install (along with copying out the etc/openhab2 directories).

Would it just be best to start from scratch with a new openHabian install and move over (and relink) my rules?