The menu is Lighter's, not ours: any perp listed on Lighter's Robinhood deployment can back a coin: crypto majors, US stocks, pre-IPO names. The catalog is re-synced from the venue as markets are listed, more than 50 markets today.
At launch the creator picks the market, the side (long or short) and the leverage: 2x, 3x, 5x, 10x, 20x, 25x or 50x, never above what Lighter allows on that market (50x on BTC, ETH, SPY and QQQ, 3x on the newest memecoins). If the venue later lowers a market's cap below a coin's leverage, the keeper stops opening and says so on the coin's page until the leverage fits again. Positions run isolated margin: a coin's position can only ever lose the collateral it has posted, never more. Higher leverage means faster burns on a good call, faster liquidation on a bad one.