The question is whether Immigration Authority demands a Valid Job offer while Job offering Companies demand Canadian Citizenship or an authorization letter to work in Canada. if this remains then how can I could a Job or immigration in Canada?
You can immigrate to Canada without a job offer. A job offer is not mandatory in order to qualify and apply to immigrate. To provide one example, a job offer is not mandatory for the Express Entry / FSW immigration program.
PR or citizenship is not necessary to get a job offer. While it's generally not easy to secure a job offer in Canada as a foreign worker, it's certainly possible and people on this forum have successfully done this (especially those with specialized education, work experience or skills). If you want to try to secure a job offer, then you need to keep applying for roles in Canada and hope you find an employer willing to go through the process of hiring a foreign worker.