Yawning Portal into Homebrew Adventure

Howdy! We have a Friday evening D&D game that is looking for at least one player, but preferably two or even three to fill out gaps in the group. We are currently level eight and going through the book Tales from the Yawning Portal. The primary DM is setting the story in his own world and making the appropriate changes to the stories and encounters within. I, the co-DM, only help with balancing encounters, story hooks and paint most of the minis that are used in the game. The plan is to get through the book and the optional level twenty encounter at the end with the players learning about his homebrew world as they progress. Then at the end, launch into a potentially longer, fully homebrew adventure set in his world. Most things are allowed from 2014 fifth edition, minus some things that simply wouldn't make sense in the world (Warforged, some Planescape stuff, a small handful of spells, the modern equipment in the DMG, etc.). We do however use some third party resources to fill in gaps and plenty of homebrew and Unearth Arcana rules as well. I cannot justly describe his world, but it is inspired by Final Fantasy XIV, some of the earlier Tales game, and has achieved steampunk and early 1900s-era levels of technology that works in tandem with magic. It still has plenty of high fantasy tropes and stories, but can also be more gritty and low fantasy just as easily in parts. We try to have some of each and have them flow together in a balanced way. The game will be held on Fridays starting at 6:00PM EST, hosted at a game shop we both use. The game uses physical miniatures and roll out battle mats, but online character creation (most players use Dndbeyond, but it is not required so long as we can access and view player sheets). Everyone at the table is late twenties to early thirties, nerds who like fantasy and sci-fi, can get a bit loud but try to be friendly, and love collecting new, shiny dice as often as we can and showing off the best ones. We try not to discuss real life topics at the game and would welcome anyone to our table as long as they're there to play a game and have fun.