I feel like although sideloading could be correct term maybe but at the same time as the author stated, people might refer something shady to something which is a genuinely normal part, maybe even more safer when you download from f-droid compared to play-store

I feel like you are having this discussion in good faith which is really nice but I just feel like saying that google is oppressing other open source appstores or just using the word installing and later clarifying can make the people feel about how dangerous it really is.

Let me be really clear. If Google can prevent sideloading and the only feasable way for 99% users is their play store which uses their policy terms which can be ever changing, chances are, that they can also prevent people from downloading your app, and can remove your app etc. as well so they can very definitely prevent installing in general as well

The only escape hatch is maybe adb but please, for the 99% of use cases, I doubt how many people would operate a computer open up the terminal and try to use adb or other scenarios, but in all ways, I think that speaking of it as an installing itself isn't so bad after all.

If Google can genuinely go ahead and do this, it would definitely prevent installation of certain app in and in of itself because play store is also controlled by google and they can also remove/prevent apps installs from there too.

I would still recommend to you / the community to say it as an installation as earlier I was also used to saying sideloading but it was only while writing this comment when I realized of how google can actually prevent installation from play store as well since they own it, its an effective lock/restriction in installation itself for all purposes.

Have a nice day.