How do you know how useful I think it will be and in what ways?

F-Droid exists. People installing APKs exist. In some cases these options are better than literal nothing, and especially if momentum builds around these it's possible that app developers may notice.

For lineage, it is popular to install Google Play anyway. I guess that to be a copyright violation that Google looks the other way for and if a real world competitor did this they would crack down.