Because there's no totalization agreement, can I get my US Social Security taxes refunded if I leave before qualifying?

Generally no. US Social Security and Medicare taxes (FICA) are not refundable simply because you leave the country before earning the 40 credits needed to draw a benefit; the money is not a personal account you can reclaim. The narrow exceptions are cases where FICA was withheld in error, for example on wages of certain F-1 or J-1 nonresident students who are exempt, in which case you file for a refund from the IRS (via your employer first, then Form 843). For H-1B and other resident workers, the taxes are correctly owed and gone. If you accumulate at least 40 credits over your career, you can potentially collect a US benefit later even while living in India, so tracking your earnings record with the SSA is worthwhile.