Apple Pencil markup not appearing after email recipient opens PDF document

Simply put - any markup made to a .pdf with iOS native apps can only be seen when opened with another native apple application.

i.e.

• saved a file to icloud
• opened file on ipad pro and marked up with apple pencil - saved file
• opened file on OSX desktop with preview - markup is visible
• open same file with google chrome - no markup

The only solution I have found is to use a 3rd party PDF app.

Surely, I am doing something wrong? Having to leave the apple ecosystem for something as simple as this can't be real.

right?

Thanks for any help in advance!