In Poland, Bison Grass vodka and apple juice are a classic combo, here also with an additional splash of Polish honey liqueur.
Adjust the quantity of...
If I cannot get my hands on bison grass vodka, can I simply go with twice the amount of the other vodka of my choice? If I also add in tea-flavored bitters, or even real herbal tea, can I reconstruct the flavor profile of the missing bison grass vodka?
Bison grass is so aromatic that I don't believe you will be able to replicate the flavour with another product. Have you tried online shops such as thewhiskyexchange.com who may ship to your region?
...and I would suggest trying polish potato vodka for this one, eg. Chopin or Luksusowa. Potato vodkas are more creamy and subtle, it would reduce the booziness.