With firefox or a hardened fork of firefox (like mull/fennec/iceraven etc.) there is a button in settings where you can install/add to homescreen and have an app-like experience for any site including instagram. (Not sure if this is on ios though.) You can also have noscript, ublock origin, and privacy badger addons running for a bit of extra protection and as you said email alias and vpn at all times. If you’re on a hardened OS like CalyxOS or Graphene you can also sandbox or work profile the browser to add another degree of separation.
You may run into problems during signup because meta has been known to use viseo/photo upload verification for accounts made with alias emails and/or from a vpn IP, but once you’re in there shouldn’t be an issue. If there is, you might want to bite the bullet and sign up in a normal way, then use privacy measures to mitigate data collection, depending on your threat model.
I did a deep dive into frontends because I love organizing stuff in general. I use different frontends for each device I have because they all have different pros, but overall my favorite is Playnite because of its metadata and sorting features. For Windows I use Playnite, on Linux I use Pegasus, on Steam Deck I use RetroDeck/EmulationStation, and on handhelds I use Knulli Firefly.
Playnite is imo the king, because it has really beautiful themes with custom cover art and can sort games in basically any way possible: by system, rating, genre, name, release date, you name it. The only con is that it’s Windows exclusive (for the near future) and is janky in Wine/Lutris.
Pegasus is spectacular for its fine grained control, and can be configured to do basically anything. Its like the Arch Linux of the frontend world; start with the basics and build from the ground up. With tinkering, it works great on almost any platform.
RetroDeck is great because it’s plug n play. I love to tinker, but I also wanted a platform to just play my games without hastle or messing around. I find myself actually playing my games on the deck instead of tinkering with the frontend.
Knulli Firefly is great for smaller screen handhelds for a similar reason. It’s very customizable, but also works straight away with little to no hastle. It’s also better than most stock OSes that ship with emulation devices