Last year for 2018 returns, certain qualified users were offered refund advance amounts on prepaid Visas at the time of e-filing, predicated on the amount of the refund and their returns being accepted by the IRS. But it had to be offered--there was no way to opt in by request. If they offer a similar program for 2019 returns, do not expect to see it until January. Since a return cannot be e-filed and accepted until the end of January, you could not receive a loan until early February at best.
As for trying to prepare your return without a W-2:
CAN I USE MY PAY STUB TO PREPARE MY TAX RETURN?
Please do not try to use your pay stub to prepare your tax return. It will not match the W-2 that you will get from your employer in just a few short weeks. Your employer has until the end of January to give you your W-2. By waiting for your W-2 you will be able to file accurately. If you try to guess what goes in the W-2 “boxes” and mess up your return, you will need to amend. It takes about 4 months to amend a tax return. The IRS will not be accepting 2019 returns until the end of January — so you can wait for your W-2. If you are hoping to get a quick tax refund by filing early, using your pay stub might have the opposite result. Your tax return will not match the W-2 reported to the IRS by your employer; this may result in rejection of your return — or if accepted, could actually delay your refund for months. And, if you are hoping to get EIC or the refundable amount of the child tax credit, your refund will not be released until late February anyhow. It is much wiser to wait for your W-2 and file correctly.