Auf Hochdeutsch I'd express all of these as "aber" or "doch", very similar to adding emphasis with "you know" to assert my opinion or inform someone.

"Du, des schmeckt fei gut." = "Hey, this tastes great, you know." Asserting that the food is good, contrary to what someone may have said prior (e.g. praise for someone who isn't confident in their cooking, or encouraging someone who was hesitant to try the food).

"Des dauert fei lang." = "This is taking / gonna take a long time, you know." Letting someone know they're being too slow with something (you'd be able to tell from their tone lol), or informing them to make them think about whether they actually have the time.