Cheese is variable.
Ask if Spell to Power Erudites are a thing in setting. If they are, you can pick up Arcane Spells as powers, and all Divine Spells can be arcane spells thanks to Wyrm Wizard. Thus, a Psion can pick up Expanded Knowledge to learn any spell.
Admittedly, Ardents do that better, the only difference is generally lower DC's. With Linked Power Synchronicity you can manifest Psychic Reformation and access to Dominant Mantle, you can change your feats on a whim (well, it will still cost 50xp/level to do so - I'm not a believer in the XP-free reading of linked power, as you still manifest the power, just quicker). Combined with friendly progression for multiclassing, you can pick up a few levels of whatever's fun. Get yourself access to some combat friendly classes for the additonal BAB (Ardent is 3/4, so Ardent 16/Full BAB +4 is +16), or some dips.