What are suitable datasets for univariate time series forecasting with RNNs, LGBM, TBATS, SARIMA models (topic, frequency, sources)?
A dataset I used when checking the ARIMA methodology is the one you can find here about monthly air passengers history data since 1949. It shows both trend and seasonality, and it is nice to play with searching for hyperparameters (p, d, q) when implementing ARIMA.
You can find below the results I got sometime ago as a quick check (being blue the true data and red the predictions):