Wait, what, AWS has Free hosting of servers?
Yes. Amazon Web Services EC2 has several instances that are Free Tier Eligible, which means that for the first 12 months after applying for an account and creating an instance, they will not bill you if your usage stays under certain limits.
Since a minetestserver doesn't need that much resources, especially if you're smart about resources, mods, and players, you can host your minetest server in AWS EC2 for free. However, there are some catches - AWS is a very professional hosting service and utilizing it well isn't easy.
Link to start: https://aws.amazon.com/freeAWS Free Tier includes 750 hours of Linux and Windows t2.micro instances each month for one year. To stay within the Free Tier, use only EC2 Micro instances.
You will require a credit card, and a phone number to confirm your identity. AWS isn't providing "anonymous" hosting.
You will need to know UNIX basics, account management, SSH, and learn how to navigate the AWS webpages.
My advice, if you want to try this, is to use an optimized Linux Distribution that minimizes the CPU time. If you run a standard Debian, Ubuntu or other distribution, you will exceed your Free Tier CPU allocation quickly. Therefore, you should pick ClearLinux (DISCLAIMER: I work, professionally, on ClearLinux) as the best and most efficient solution(* my opinion, not necessarily that of my employer) to run a minetest server. Fortunately, ClearLinux has built in packages for minetest.
You can find ClearLinux in the AWS MarketPlace and create instances without having to upload images, and these ClearLinux images are supported by the ClearLinux Project Team. (See: https://clearlinux.org/ for more info).
Make sure to pick the t2.micro instance type when creating an instance. The instance storage can be grown to suit your needs and a reboot of your instance will automatically add the required size to your partitions.
You will need to create SSH keys and provide them to AWS so they can be put into your EC2 instance. After creating the instance, you should be able to modify the security group and open ports, add more local users, and start building your minetest server.
After a year of usage, AWS will start billing you for usage. Their billing is flexible and not based on minimum amounts per month, so if your server is low population, AWS EC2 may be a cost effective alternative hosting solution.