Found my next save! Saw 2 or 3 weeks back on reddit, someone was still playing FM23 and had won the SPL with Ross County, where everyone in the squad had Ross in their name.
I think TomFM saw it too as he's recently put up a video of the same challenge.
He just sims his seaons as far as I know, but I want to grind it out and play it.
Don't think I'll do Ross County, but there's others out there. Barry Town with a team full of Barrys or Frankfurt with Franks got mentions in the comments. I've separately seen someone being challenged to play as Stevenage with a team full of Steves. I've thought of Peterbrough, Peterhead or Zenit St. Petersburg with Peters.
Now I would allow myself a bit of leeway to include different languague versions of the name. Stevenage could include Steffen, Stefano, Estaban. The Peter team could include Pedro, Pierre, Piotr etc. Last names too - Stephenson, Stevens, Peterson, Pedersen etc.
100% doing this next.