Small update: I installed Mac OS 9.2 on the Power Mac G3, and ran the system diagnostics on it, which all passed.
I connected it to the ethernet and tried to use the internet for a while. The internet was slow back in the days of the Power Mac G3, and it wasn’t all the internet’s fault. Internet Explorer choked pretty hard on the modern web, but iCab and Classilla both work reasonably well.
I installed the Vine VNC server on it, which enabled me to (go home and) successfully screen share into the Power Mac G3 (here, I’m sharing my iMac’s screen, which is sharing the Power Mac G3’s screen, but it was also possible to just connect to it directly from home).
I then set up A2SERVER on my modern iMac (which was quite easy), added another share volume for Mac files (by editing /usr/local/etc/netatalk/AppleVolumes.default) and enabled DHCAST128 authentication so I could connect to the share volume on the modern iMac. And I moved a copy of DarkSide over to it, and set it and the Vine VNC server up as a startup items, so that when the machine rebooted it would be protected from screen burn and would allow me to share into it.
Although it mostly worked, and I was able to mount the AppleShare volume, I found that the VNC server was a little bit unreliable. If the Mac got at all busy (particularly if copying over the AppleTalk network), the connection would freeze. Generally it was no problem to re-establish the connection, but I had to do that over and over. Eventually, it was set up.
Then I tried something dorky. I copied over the Apple II emulator Stop The Madness to the Power Mac G3. [Trivia note: Back in 1994, I wrote an accompanying program for STM called SaveTM that allowed disk images to be saved (since STM didn’t do that). There were two versions; paradoxically, the newer version of SaveTM (SaveTM 1.02) only works with the older version of STM (0.851r), while the older SaveTM (SaveTM 1.00) works with the newer version of STM (0.881r). SaveTM long ago disappeared from the internet, but the new links in this paragraph do lead to the program now.]
I thought it would make a funny screen shot to be running the Apple II emulator on the Power Mac G3. However, when I launched the program, the G3 froze, and I haven’t been able to communicate with it since. I’m hoping the screen won’t be completely burned in when I get back to the office next. Oh well. There were some downsides to the days of MacOS 9.
Now that A2SERVER is set up, the next thing I’ll try is to connect the IIgs and try to netboot it (I tried to netboot Sweet16 running on the modern iMac, but it couldn’t see the AppleTalk network), then I’ll see if I can do the same thing for the platinum //e. And I don’t think I’ll try to emulate any more Apples II on the Power Mac G3.