VAC bans would be extremely unlikely, but never impossible to get. It's all about minimising risk which is up to the developers.
Onetap's developers are very good and know what they're doing. They're more than capable of keeping the risk at a minuscule percentage.
As with untrusted, as long as you have the anti-untrusted feature you will be safe.
And overwatch convictions have nothing to do with the cheat itself, its how you play and the number of reports, your score etc. that lead to your game going to overwatch which may result in a conviction.
