Sometimes only if you look for small details. The ChromeOS launcher mixes Chrome Apps, bookmarks, PWAs, and Android apps with only a small badge to differentiate if you have multiple of the same app (e.g. Keep Chrome app and Keep for Android).
But once they're running, don't they look and behave very differently? The last time I tried Android Firefox on ChromeOS, it had to quit to resize its window.
They don't really behave or look all that different. When was the last time you ran an Android app on ChromeOs? The original attempt that ChromeOs made at getting Android apps on ChromeOs back in 2015 or whatever was scrapped because it was buggy and had the sort of problems you describe.
Depends on the app. Some are resizeable and respond sensibly to mouse and the tab key. Some are stuck in phone mode.