Both XIM APEX and Titan Two work on PS5. To play PS4 games, you just need a DualShock 4 controller to connect to APEX or T2. To play PS5 games, both devices need a specialty PS4 controller for console authentication and to avoid disconnects (refer to
https://xim.tech/beta). Titan Two also supports a DualSense controller for authentication, but there's a short timeout of 800ms every 8 mins to reconnect to the console.
Both devices do a fine job of mouse & keyboard, but XIM APEX is much more plug & play, with more precise mouse aim due to mapping each game's unique look mechanics via Smart Translators, which are exclusive to XIM devices. Titan Two can get close for mouse aim, depending on the game, but requires more fine-tuning and lacks XIM APEX's extensive range of Expert configuration settings.
If you're after the best and easiest m/kb experience, go with XIM APEX. If you want m/kb and mods, but with a steeper learning curve, Titan Two is a great option. Titan Two can add mods and additional device support to XIM APEX, so many of us use both in combination.