'I eat two apples per hour' can be interchanged into 'I eat two apples each'? per=for each, each=for each. I think it is grammatically perfect.
If you say
I gave the boys an apple each.
We understand "each" to mean "to each boy"
Similarly we can say
I eat two apples each hour.
It is a lot of apples, you will get sick, but your grammar would be correct!
But without context we can't understand "each" to mean "each hour". So
I eat two apples each.
Is not correct English. It is incorrect grammar and highly non-idiomatic. You need to say "each hour" or "each day" or even "in each town" or "on each Friday"
You can't leave out important words that provide meaning not supplied by the context.