What achievements are "missable"? *spoilers*

Solution 1:

Aside from the achievement you mentioned in spoiler markup, the other missable achievement is: Saints & Sensibility, where you have to had...

Completed 'Grand Finale' with the full help of your homies.

To avoid missing that achievement...

There are two endings to the Grand Finale mission, though it is not through anything the player does in the mission. If all loyalty quests are completed, then the player will unlock the true ending where the Saints discover time travel and the narrator will be revealed to be Jane Austen. If not all the loyalty quests are completed, then the player gets the non-canonical "bad ending" of the game in which the Saints do not discover time travel and the player will not get the "Saints and Sensibility" achievement.

^{Source: Saints Row Wiki, "Grand Finale - Trivia"}

As for the Enter the Dominatrix DLC, since you can replay its missions, there are no missable achievements. You would have to finish the whole DLC to replay the missions, though. If you'd rather not do that, the ff. achievements are missable the first time around:

• All Too Easy

  Kill Zinyak in less than 5 minutes in 'Save the Planet'.

• Indomitable

  Complete 'Meet the Dominatrix' without dying.

• Rigging the Race

  Destroy all the rival pony carts in 'At the Races'.

• Health Inspector

  Destroy all the green polyps inside Paul in 'Pop His Top'.