"Cron not running" (but it is), trying to use wp-cli in crontab, with WordPress
whereis wp showed wp: /usr/bin/wp, so I tried that in crontab and the problem appears to be solved!

System Status no longer says cron is not running and the "Last Run" column on Scheduled Jobs listing shows that the jobs have run.

successful crontab entry:

*/15 * * * * /usr/bin/wp --user=cronuser --url=http://mydomain.org --path=/myserver/homepages/34/d1111111/htdocs/mysite/ civicrm api job.execute auth=0