Been to MT Surpermarket maybe twice, it’s pretty good though too far for me. 99 Ranch Market are closer and up the street from it there’s a nearby Korean grocery store called Han Yang Market. I really like both 
Also as a heads up there will be a new H-Mart on 11301 Lakeline Blvd Bldg 8 if you’re on the north side of town (i’m coordinating the gas install for them).
Vegan and Vegetarian fare in Austin post-COVID has been iffy for me as well. I feel that it’s gotten so expensive, took my SO to Beer Plant for Valentine’s Day and the prices were eye wateringly high. Another vegan fave of mine used to be Bistro Vonish, they’re great but again the last time i ate there i felt disappointed mostly based on price point.
Also in the past 2-3 years i’ve noticed a slew of food trucks and restaurants we loved close shop, particularly vegan ones. On the plus side we’ve been eating out less but i do miss it.
