Fake It 'Til You Make It

Quick and easy guide as of 10.2.6:

1. HIGHLY HIGHLY HIGHLY recommend using monk to solo this. This allows you to spec brewmaster and skip the entirety of the Sol'eah fight.
2. Set dungeon difficulty to Heroic and enter.
3. Kill first boss, head right down the stairs and in a corner, buy [item=185953] from a [npc=180754].
4. Head to the Au'Myza's Oasis area and progress until you are able to enter. After entering, to the left after the stairs, find [npc=180750].
5. Equip [item=185953] and speak to him. He will transform the neck into [item=185954].
6. Leave the dungeon, reset instances, and re-enter on Mythic difficulty.
7. Before moving, use [item=185954] to transform into a broker, and speak to [npc=180322] to your right, and exhaust dialogue.
8. This will allow you to speak to the guard and enter without fighting.
9. Progress dungeon as you normally would.
10. For So'leah, she will take 99% reduced damage for the entirety of phase 2 if done solo, which is why brew/monk is recommended. Touch of Death will allow you to skip the entirety of her phase 2, saving tens of minutes of time.

For anyone wondering, you can activate hard mode and then talk to Ta'piks to skip to Stormheim and kill only the last 3 bosses, our group just did it that way. We did kill the first boss before skipping, might need confirming on skipping first boss, but definitely don't need the next 4.

Easy Solo Achievement for Level 70 Dragonflight & Beyond...

1) Mythic Hard Mode Difficulty.

1b) To obtain Hard Mode Difficulty for Tazavesh, the Veiled Market, head here and complete the steps: https://www.wowhead.com/guide/hard-mode-tazavesh-guide-how-to-activate-boss-strategies-rewards

1c) The instance must be fresh, so with killing the first boss from before to obtain credentials, you will have to wait a week.

2) Finally, the time has come. Head to Tazavesh entrance but don't hop in yet. With your Passably-Forged Credentials equipped, you will see Fe'tajid--talk to him at the start of the instance to enable Hard Mode.

2b) There used to be a way to skip all the way to the final 3 bosses, I am unsure if that still worked or not, as I did not do it.

2c) I do not know if the necklace had to remain equipped or not, I kept mine equipped just in case.

2d) There are plenty of battle pets in Tazavesh, the Veiled Market that you may have been unaware of. Feel free to capture them for some more pets to add to your collection.

3) Clear the instance to the final boss.

4) Nuke the final boss. In Solo mode, a shield on the boss will be up yet you will still be able to damage the boss, however very slowly, so grab a coffee, this will take a few minutes at Level 70 Dragonflight.

5) ?

6) With the final boss killed, the achievement has popped and you also have received the coveted Tazavesh Gearglider mount. Congrats. Achievement Completed.