Why not get tobacco? Try Seedman 506 as a starter for tobacco DIY:
Tobacco Flavorings for Home Grown Tobacco
Note that their site is specifically "don't ask us about using our flavorings for vaping". They actually sell flavorings that are used to flavor tobacco [emoji3] That said, their 506 ia great base flavoring,
(I used Seedman back when I first started DIY, was never tempted to try any other tobacco flavors.)
Along with the various Seedman tobacco flavors (that aren't going anywhere - they aren't marketed for the vaping market), some tobacco absolute, used at TINY amounts (a couple drops per 30ml) adds a bit of bite to a tobacco eliquid. I see it available here:
Tobacco Absolute 100% Liquid Concentrate