The full screen thing -- have you tried saving the SPA to the home screen?
Together with some meta tags, that launches full screen and stays full screen, like an app.
The bashing on apple for this "to sell more apps" is nonsense, Apple originally designed and intended for HTML5 apps to beat Flash.
One of the earliest games for iPhone was PacMac, it was a SPA web app saved to home screen, it worked great.*
OTOH, in 30 years of web dev, I never got pages about raccoons to work either.
* Haven't checked this lately to see if they deprecated this.
> The bashing on apple for this "to sell more apps" is nonsense, Apple originally designed and intended for HTML5 apps to beat Flash.
Whatever their apparent intention might have been ~15 years ago, it would be hard to argue that Apple puts a lot of resources into trying to protect its fiefdom. I don't think it would be all that different to suggest they (Apple) wouldn't try to control how people pay for apps by preventing app developers to offer a web-based payment option, on the basis of their past relationship with HTML5. A huge component in their success with iPhones has been control over the entire supply chain.
That said, it is a somewhat conspiratorial take that is probably better explained by laziness, bad choices, and control over proprietary UX patterns (that suck), than generalized competition, but it's not much of a reach. They also compute localStorage limits differently and have always diverged for stupid reasons
Home Screen Safari and Browser Safari act very differently.
There are a lot of bugs where home screen safari passes feature detection but in reality does not work.
iOS and Safari are hell.