The oil grade will be in the handbook - probably an ordinary 10W-30 oil.
"I know it’s not recommended in my Honda Izzy mower" All Honda petrol engine products will run on standard unleaded SP 95. Check your handbook again.
It's a four stroke engine. It needs ordinary SP95 fuel (unleaded) - (don't use SP95-E10 because it's cheaper - it's crap and will mess up the engine in storage)
You are worrying me a bit with "What’s the recommended mix ratio?" - You don't need to mix anything with four-stroke fuel.