It depends on the instance. I created an account on mastodon with guerillamail which would be even more suspicious for an average website than your alias email. A tip, if you do not mind using icloud email, you can even create one with some effort without giving real personal data and using apple hardware (Virtual machines ftw), you can take advantage of its free alias email addresses which would be accepted even on most strict websites.

You can try and later post peertube/youtube link. Nobody can really guarantee that it will be interesting for them until they see it.

The apps need permission to the microphone for that and in background it would drain the battery and constantly show the microphone is accessed unless you are using an old android version. It is likely easy though to eavesdrop when the app is opened and using microphone is an expected functionality, and to pick up keywords and the sounds emitted from other sources to better know location and social graphs without GPS access.

Google itself as of this moment never did put adds on a lock screen, it is the manufacturer or third party apps who can do it. Some Realme and Xiaomi phones do it afaik and probably some other brands.