Hmm, how does an icon get there? Any icon that gets added to my launcher gets added on some page >2, the first 2 pages are reserved for widgets (I can manually move an icon for a program on page 2, but I never do, an icon will never be auto-placed there either), and this is the bog-standard android/google pixel launcher.
And no need to look up, it is trivial to link straight to an app, Pie even has a quicker mini-launcher that can install an app without even leaving the browser or whatever. 
That’s definitely not a standard setup, I’m guessing that’s Twitter (I don’t use twitter outside of the terminal)? I’d lean more toward the left one as the bottom bar is the modern design that should be followed, however the design of it implies that neither are native, or at the very least not using the recommended API’s. Having a program that ‘interacts’ like the platform standard is very important to make an app feel comfortable, that’s one of the tenants of the Flutter framework by google for example (yay no xml horrors).
But yeah, neither ‘look&feel’ native by any stretch.
As for installing, well I search ‘twitter’ using the search bar at the bottom of my home page and the very top big obvious thing is an ‘Install’ button for twitter from the play store, clicking it brings up a little screen in the enter of my screen giving a little bit of information, the ranking, download count, I can click on the image to bring up the full view or hit install to install it right then and there, it took about 2 seconds (I’m on wifi), and I now have a notification on my phone to launch it or I can swipe it away. That doesn’t seem even remotely difficult, it took a couple of seconds and it was guided the entire time. Twitter on the other hand isn’t even letting me log in, no message or anything, I put in the 2fa and all and it just goes back to the main screen, great program there… oh wait, closing and reopening it and I am now logged in and seeing things, the heck? o.O
Let’s see, can swipe in, search bar is in the wrong place, bottom bar is good, can’t swipe between tabs, why are so many people following me (o.O?!?), the animations are ‘wrong’ (not following what I have set in the system, and they are too slow as I have them sped up globally.
It seems about half-native in feel, maybe some ancient android version in feel or something. Significantly smoother than a webapp though (Facebook’s app is just horrible, I’ve tried their PWA and native both and both are just absolutely horrid in quite a number of ways, especially battery usage somehow…), but twitter’s native app at least seems responsive if a little unusual in layout.
Likewise, a link is fine, some hovering popup on the screen or at the top is annoying as heck and will definitely ensure I don’t install anything.
Exactly this, this is the modern android homescreen standard, as said above no icon will automatically appear on the first 2 pages. The first page being google’s AI thing and the second being my daily widgets. Launching something is either a quicklaunch at the bottom, or I swipe up and hit one of the 4 ai-selected apps that it thinks I want, or I can search or jump straight to a lettered section or whatever, it’s all super fast and I can do that swipe-up thing from any screen (consequently I’m almost never at the homescreen).
The play store for CERTAIN, programs there go through a LOT of checks, sure some malware makes it through but most does not and most get caught soon anyway. Going to some url and ‘installing’ something from there without ever seeing the play store would give me a very immediate cause for concern and I’d be looking for how to undo that immediately.
Never install an app without going through the play store, doesn’t matter if it’s a little web link that is set somewhere or not, just Do Not Install Anything Without Going Through The Play Store, big security issue otherwise.
As stated above, both look non-native and horrible. 
Precisely this
Ooo great point here, didn’t think of that but that would bug me too if I started using them…
