IRA withdrawals and taxation as non-resident alien

Your question is really several unrelated questions which depend in part on some unknown facts. So I'll try to summarize:

First, you mention you moved out of the US in January 2019. Unless you meant December 31, 2018, you may still be a part-resident, part-nonresident in 2019 (for tax purposes), depending on what made you a tax resident to begin with.

A contribution to an IRA in 2019 only makes sense if you have potential US tax liability to begin with. If not, there is no point in making an IRA contribution because...

When you are 59.5, receiving IRA distributions will generate US source income.

Note that there is a US-India tax treaty and that may change these results (I didn't take a look at it).

And, of course, there is Indian tax law to consider as well.

All in all, it's not that simple. Reading this may help a bit.

401(k) should be rolled into an IRA once your employment relationship ends since 401(k) is an employer-specific savings vehicle. IRA can be rolled into Roth IRA in any year where your US tax liability is low.

When you are over 59 1/2 years, the traditional/Roth IRA distribution can be taken as periodic payments and treated as a pension. Some IRA trustees are finicky about treating the IRA as a pension. In that case, you can buy an annuity within the IRA. Pensions/annuities are taxed at 0% (not applicable if its a lumpsum IRA distribution) when being distributed to NRA resident in India as per the US-India DTAA. The IRA income distribution will be taxed as ordinary income in India but probably at a much lower rate than the 30% default withholding for all distributions made to NRAs.