If you just want futures, you can use Tradovate's market reply which I believe costs $30/month, mostly free.
Ninjatrader used to offer this for free on their platform, but not sure if now you have to fund an account first with their brokerage arm.
It's cool and it's right that you're interested in some things that will allow you to practise and gain some new and useful experience in a safe environment. Investing is quite a complicated field that makes you vulnerable and forces you to make decisions that can lead to different consequences, so the better you get at it, the better. The key is to find the analysis methods that you can use that will help you best understand what is going on in the market and how you can keep your capital as safe as possible. I think there are enough opportunities today to learn everything you need to learn and not lose interest.
Given that only crypto-assets are available on the market at the weekend and you're looking specifically for a simulator, you can practice on any demo that is available from your brokerage company. In general they behave more unpredictably, on the other hand it also allows you to experience some difficult moments and learn to control it, so it can be a positive experience. I just don't understand why you are interested in working only on weekends, because on weekdays there is much more news and events that strongly reflect on the market and therefore allow to see the market in different states, so don't limit yourself to get a fuller adaptation to the market. Good luck to you.