Is there any support for QOZ investments for 2019? I don't find any reference to Form 8997 on the TT site, which is required by IRS to defer cap gains.

No, there is no support for Qualified Opportunity Zone investments and you can't file Form 8997 using TurboTax.

Are there other tax software vendors that support this investment type?

As of now, turbo Tax does not support Form 8997. I do not not know if other vendors support this as it was recently released. 

Form 8997 is not listed in the "Which IRS forms are not included in TurboTax?"https://ttlc.intuit.com/community/forms/help/which-irs-forms-are-not-included-in-turbotax/00/25551   However, it is not available in today's software release.  TurboTax shall keep their promise  to get its users covered to include it in the next TurboTax software update.

Taxslayer claims support: 

https://support.taxslayerpro.com/hc/en-us/articles/[phone number removed]-Form-8997-Statement-of-Qualified-Opportunity-Fund-Investments

Promise?  Is this truly a planned feature?