Technology on Myra is on a comparatively low level also (many human nations are not above what you'd find on earth in the early middle ages between 500 and 1000 AD). More is possible though, basically what would have been possible in the middle ages, not what actually was there. Three notable exceptions, though:
(1) a magnetic compass would not work, as there are no magnetic poles in this world. This makes sea-travel slower and mostly coast-bound.
(2) gunpowder would not work as the Powers-that-be have ruled that out
(3) glass is (and thus effective mirrors are) only available for followers of the demigod of light and good magic, Seeker, the hermit in the desert of Zun. The mystery of glass-making is a well-kept holy secret, not common knowledge.