The combination OpenOCD / GDB for the STM8 appears to be a bit inaccessible. In fact it's a really good "text adventure game", and I've had fun finding my way in a "software landscape" with a long history and a specific patois.
It turns out that one can set breakpoints or watchpoints and inspect memory with OpenOCD alone - GDB required for that, and instead one can use commands from the built-in gdbserver through a telnet session. The combination of STM8-GDB and OpenOCD can replace stm8flash for most (if not all) use case. I guess that writing STM8 flash, configuration, and option bytes with a script, instead of using GDB, is possible too.
New applications, like writing a tethered Forth that runs on a PC and interacts with the target device through OpenOCD is within reach, and it might be interesting to explore work by @Lars Brinkhoff and in that direction (@RigTig once started there).
What's more, both OpenOCD and GDB are scriptable. OpenOCD in the TCL dialect Jim (Rule #1: Everything is a string, Rule #2: If you think otherwise, See Rule #1).
I guess it's about time to get one of those unloved STM8L101F3P6 and STM8L001J3M3 devices from the basement. Maybe I now have the tools to program some Forth into them :-)