I agree, the 555 is not well suited to this application with real
components.  Additionally,  10M resistors are trouble because of humidity
and pcb contamination issues.   If i had to solve this problem,  i would
use one of the six pin AVR controllers like the tiny4 running on the
internal r/c oscillator.   You get four I/O pins and far better control of
the output.  Not as much drive current and a more narrow power range, but
that may not be an issue for you.

FWIW.
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