[Timon3]

Of course you could put apps on phones before app stores. Distribution etc. was harder, and most applications were much more limited (especially due to worse performance, network connection, and limited input methods), but a whole industry existed - there were even communities around "jailbreaking" and so on.

[Angostura]

and you can still jailbreak now if you want to. But even with a jailbreak, I’m not sure there apps, as opposed to tweaks that you could put on the iPhone.

[Timon3]

> and you can still jailbreak now if you want to.

I can currently only jailbreak an iPhone due to mistakes made by Apple. It's conceivable that it won't be possible at some future point - though I'm not sure how this is relevant towards your earlier point?

> But even with a jailbreak, I’m not sure there apps, as opposed to tweaks that you could put on the iPhone.

There have been very limited workarounds on iPhones to enable sideloading, e.g. AltStore. These repositories are exactly the kind of apps you're looking for. But again, not sure how this is relevant towards your earlier point?