Just found this debugger...

[tide]

On Wednesday, 3 October 2018 at 13:20:03 UTC, JN wrote:
> On Wednesday, 3 October 2018 at 03:25:04 UTC, solidstate1991 
> wrote:
>> Then I had a thought: Is there anything usable on the market 
>> besides these?
>
> It may not be enough for your needs, but VSCode C++ debugger 
> somewhat works for D. I can't set breakpoints, but stepping 
> through code works and watches also work for most simple types.

Enable the setting in your user/workspace:

   // Allow setting breakpoints in any file.
   "debug.allowBreakpointsEverywhere": true,