As long as you study B.Tech from an AICTE approved  and recognised Colllege, your B.Tech is valid. In 2019, the Supreme Court passed a judgement that any College claiming to provide B.Tech through Distance mode should have recognition and approvals from AICTE. So that way, B.Tech is valid even if you study through Distance mode. Regarding the opportunities for appearing for entrance exams. CAT has no disparity between Regular mode Bachelor's degree and Distance mode Bachelor's degree. Regarding GATE, it also implies the AICTE approval and recognition rule but doesn't specify anything about Regular mode or Distance mode.

Academy of Higher Education

Wisdom School of Management

IIMT Studies are few Colleges that offer Distance Education for B.Tech.