Are there any bitcoin ATM's in Vilnius?
There is no Bitcoin ATM's now in Vilnius and whole Lithuania. There was few Bitcoin ATM's in Vilnius, but it were removed few years ago because of some regulations issues.
Judging by the comments on "this listing" in CoinATMRadar, it seems that there's still one left.- After expanding its feedback section, the last comment appears to be from 5 months ago and it has a "Longlasting Available" status.
I want to buy few bitcoins totally anonymously. Just for experiment 
You can buy fractions of BTCitcoin through a BTM anonymously, but you can never buy a "few of them" without having to go through some kind of KYC process!