So Malon kindly gave me Deku Seeds instead of the egg.
Unable to wake Talon, I headed to Kakariko where I received Bombchu's for rescuing the cuccoos - dead handy. I used a couple opening grottos and things and then had a thought, I can get to Dodongo's Cavern via the woods without needing Zelda's letter. This wasn't as successful as I'd hoped it would be - although I did make it, there are so many bombable walls and I only have a few bombchus, I'm not going to make any real progress here before running out.
So instead I took my last couple of 'chus and opened the pathway to Zora's domain. Thankfully the seed seller sold me a Fairy Ocarina for 60 rupees! I already found a couple of songs in random places, luckily including Zelda's lullaby and Saria's song, which opened Zora's Domain and allowed access to Darunia. Neither of these gave me any useful rewards - but no matter, I soon got lucky and found the Song of Time in a grotto.
This is where I've hit a wall unfortunately. My next move was to try becoming adult Link, and in the cutscene in the Temple of Time after growing up, Sheik became stuck in a dialogue loop.
A very quick search suggests I'm not alone in this and it's a problem with Project 64 - anyone else had anything similar?
It's a shame but I enjoyed what I played. I should also say I did have some issues using the tracker and have ended up just using it as a reference rather than it using it properly. I might try fiddling with it some more if I start another run.