This is supported by the fact that there is currently no gift tax in Austria.
When making a gift, you can have a right of residence entered in the land register for yourself and thus continue to have the right to live in the gifted apartment.
You can prevent your child from selling or encumbering the apartment during your lifetime with a prohibition on encumbrance and sale.
You must bear in mind that the gift may lead to inheritance claims by your other children or your spouse.