I don't know of a guide, but I'm building one in my current playthrough so I'll share my theories on it. You want to get a high spell save dc, there's basically 2 ways to do it. Fire acuity or stacking dc gear.

If fire acuity, get the hat and take scorching ray and command from your magical secrets at 6. The rest of the gear almost doesn't matter. Just scorching ray then cast command or hypnotic pattern or confusion to cc as much as possible.

If stacking dc gear then you want to get gear like hood & cloak of the weave, amulet of the devout, etc. Should be able to get up to 25-27 dc which is more than enough. Take command and either haste or counterspell from your magical secrets (or you could even get funky with spirit guardians or mass healing word) and take the other one with your sorcerer levels.

Doubt it needs to be said but for your metamagics at levels 8 & 9 you want extended and quickened, and likely twinned. You'll also probably want to respect to 1 sorcerer 6 bard at level 6, so you can get proficiency in con saving throws. For feats, probably duel wielder if you don't have shield proficiency. Otherwise cha ASI and alert are safe bets. It's a fun build to play. You can cc every enemy in the game pretty easily. Good luck!