if there any community channel or webpage which consists of multiple robotics, IoT, and ML projects for practicing so that I can use it for project reference
Please click the link below to resolve your issue.
[Bolt IoT Project Page] (https://www.boltiot.com/projects)
I hope the above link provides you with sufficient information to help you decide.
YES, you can use GITHUB for any kind of projects and bolt cloud for bolt iot based projects only.
Also, check Bolt IoT Workshops