Search engines are websites that people used to go to in order to get helpful information. These days, they just spam out a bunch of SEO garbage, AI-generated bullshit, and ads.

Google, probably

Yes, a lot of developers have done this. Many examples have been posted on this thread (OsmAnd, Conversations, Davx5) - Mindustry is another example. free on f-droid (and Google store too I think), but $10 on Steam.

Xournal - a great way to draw on pdfs

Wow, these new TLDs are terrible! ICANN has really lost it this time!