The claims here do seem a little suspicious, for one CoreMark is not the be all and end all of benchmarks, especially if you're trying to compare yourself against the M1 and other CPUs in a similar class. You need a far broader base of benchmarks for a decent comparison (for one thing CoreMark won't give the memory system much of a workout).

A big red flag is the Cortex-A9 comparison that is used, being described as the faster arm processor for CoreMark, if you go to to EEMBC's CoreMark score database (https://www.eembc.org/coremark/scores.php), search 'arm' a Cortex A9 part does indeed take top score. Note this are just user sumbitted scores without any real curation, searching 'arm' isn't guaranteed to give you all arm cores in the database, plus results could have errors in.

Given the age of the core (it was introduced in 2007) I'd be rather surprised if the A9 was the best performing arm core on CoreMark. Though From a quick google I can't find CoreMark numbers for other arm A-class cores.