The Reccurent ETDS (online) seminar: https://sites.google.com/view/recurrentetds/home (by Nishant Chandgotia and Shilpak Banerjee)
Database for researchers and conferences in dynamical systems: https://www.ergodictheory.net/ (by Stefeno Luzzatto and Tanja Schindler.)
An audio visual broadcasting for mathematics: https://www.carmin.tv/en/
Living Proof: Stories of Resilience Along the Mathematical Journey
What is mathematics? (by Richard Courant and Herbert Robbins).
3 Blue 1 Brown youtube videos.
What are Lyapunov exponents and why are they interesting? (by Amie Wilkinson).
The Princeton Companion to Mathematics, edited by Timothy Gowers.
Visual Complex Analysis, Tristan Needham.
Books by A. Y. Khinchin.
Differential forms and applications, P. do Carmo.
Fractal geometry, Kenneth Falconer.
The Atlas of the Invisible - James Cheshire and Oliver Uberti.
My Favourite Theorem - Kevin
A Brief History of Mathematics - BBC Radio 4
How to PhD
The Moving curve - Rukmini S
Articles of Interest - Avery Trufelman
LeVar Burton Reads
The Happiness Lab with Dr. Laurie Santos
A student with a thirst for science can pursue it from anywhere, whether its your local library or on youtube.
If you are finishing your 12th standard, BSc or Msc in India, there are many reputed science institutes that you can aim for.
Listed below are some such institutes:
Chennai Mathematical Institute
Indian Institute of Science
NISER, Bhubhaneshwar.
IISER
BITS Pilani (Pilani, Hyderabad, Goa)
TIFR
IMSc
Pondicherry University
IITs and NITs (You probably know this already)
CSIR-NIScPR (specifically for science communication)
The following are some of the scholarship exams that are worth attending for the sheer exposure that it can provide, to a student who is constrained by the state board or CBSE syllabus.