Hey, welcome to the forum, and thanks for asking.
We are working on adding stocks like Wizz Air, and other highly-requested companies like easyJet, IAG and Rolls Royce, and will add them in the near future.
They are a bit trickier to add from a technical point of view, due to something called nationality declaration.
Some more on this is below.
In the meantime, you can explore the 1,600 stocks and ETFs currently available on your Freetrade app on this link below (including many international travel companies like major US, Chinese and Latin American airlines, Chinese travel giants like Trip.com and global comparison site TripAdvisor, to name a few).