You can prepare standard question answers that have been asked in interviews for your job designation. ChatGPT can also help you find the good questions for the interview.

About rejections, don't take it seriously. Consider it as part of learning and you can even ask them at which area you should improve.
Sometimes they just don't have the budget to hire you or they may hire another person with your skill set but with a lower budget.
So, there are many reasons for the rejections. Don't let it overwhelm you.

For free text based, there is one app called solo learn it also has a website.
W3schools is also a good website for beginners.
For video lectures, freecodecamp is good YouTube channel to watch.