Google Cloud Shell
Google Cloud shell gives you 16 GB RAM Intel(R) Xeon(R) CPU @ 2.20GHz free for lifetime. The main problem is, that you cannot run something in the background like if need to do fuzzing on big targets. If you close the browser tab, it will destroy the session but your files are still saved inside this. So enjoy 16 GB VPS for free https://shell.cloud.google.com/?project&pli=1&show=terminal
Free Trial with Credit Card
If you have a credit card, then you can get free trial of DigitalOcean and Linode for 8 months for free. You will get 4 GB RAM VPS which is enough for bug hunting.
If you are looking for cheapest VPS, check this https://contabo.com/en/.
It's giving you 8GB RAM VPS for almost 100 USD for 1 year which is cheaper as compared to DigitalOcean/Linode/AWS. They have a 1-year contract which means you have to pay and use it yearly-wise.
Android as a VPS
Yes, you can turn your Android into VPS with this APP https://play.google.com/store/apps/details?id=tech.ula&hl=en_IN&gl=US
If you have 4GB Android, you can use Kali linux in that using UserLAnd app. The main issue here is that your Android apps will also consume RAM, so you will not get much RAM here. But still you can do stuff like fuzzing 24/7 using you phone.
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