I have got it working and there were 2 things which might went wrong.
I might have picked the x86 instead the x64 version of the php and/or Apache server install package. I reinstalled everything from scratch.
in the httpd.conf make sure the command is
LoadModule php_module "C:/php/php8apache2_4.dll" not php8_module
Problem solved for now, but I have another small annoying thing which I post as new topic.
p.s. the settings in the IIS to have things running were a nightmare