I'd say give it a go regardless. Stovetop should be fine to just chuck in with some tonic. I'd imagine with a pour over you'd want to use less water and a finer grind than normal to offset for the dilution you'll get with the tonic. Similar to making a pour over over ice
You want a concentrated brew - I never had great results with pour over. Stovetop would be fine. A strong french press or cold brew would also work fine
On the espresso tonics… Is there a method using a stove top or pour over? Or is this espresso only bsns?