You are correct that, if you held PFE, this was a non-taxable spinoff of VTRS. It can be entered using the Spinoff button on the Accounting>Investments page.
On 11/17/2020, for each share of PFE you owned you received .124079 shares of VTRS. If you were owed fractional shares, you will also receive cash in lieu of them.
It is still early so tax information describing the basis allocation between the two stocks has not been released by Pfizer yet, so you will probably only be able to make a temporary entry.
In this case, use the "Default" remaining basis percentage calculation you'll find on the spinoff entry page. Then adjust later once tax information has been released or your broker has provided final cost basis data for both sets of shares.
We are glad to help you make the entries you need if you send cost basis information from your broker to email@example.com
As with all reorganizations, it is very important to verify that the cost basis of each lot of each stock received after the reorganization shown on the bivio "Investment lot cost basis" report agrees with what your broker shows on an "Unrealized gain/loss" report showing similar details.
Note that if you owned MYL shares you also received VTRS shares, but that exchange was taxable and would be entered differently. Contact us in support and we'll be glad to help you get those entries made also.