thats actually a fair question, no technically if you declare you're going to attack with both weapons, it doesn't matter if you use the bonus or the standard first. Because you already declared both. Not sure how you'd implement that in BG3 though, other than after using bonus action attack, disabling everything except the attack option...
i liked the flexibility of taking offhand attacks first. i had a dagger that gave bless on hit that i was using in my offhand so i was making offhand attacks first so that my main attack would be blessed.
So long as the only action you can take after attacking with the off hand is attack (i.e. no dash, no casting spells, no using items (all of which SHOULD be actions, not bonus actions)) it'd be fine. Technically Shove should be an option that can replace an attack, but it shouldn't work like it does right now (right now, it too is pretty OP and silly). So shove in theory should also be an option after a bonus action off hand attack.
In pnp, there isn't a concept of "off hand" either though for 5e, you just choose which hand to make your attacks with each turn, and if you have something in the other, you can attack with that once as a bonus action. So in your example, you could opt to attack with the bless dagger first as an action then your other weapon as a bonus action in pnp.
