Lizardfolk has me completely stumped RP wise. I really like the idea of a Lizardfolk - Cleric of the forge from Xanathar's. The thing is... this race just doesn't care about anything except survival... They don't want or desire anything from what I understand.
Do these creatures have religion? Since they have no moral system or want/need for anything greater than living, would it even be possible to explain how one would be a cleric?
Also, how would I RP them? Do they speak in first or third person? How do they interact with others?
To me the idea of lizardfolk is to be playing a different mindset. As Volo describes them, alien is frequently used.
Now we have all seen character, pc, npc, etc who did not develop attachments beyond practical, right? LF take that to the core.
As for how that religion would work, it would be about powrr and the need for power to survive. LF could see the power of enemy clerics and warlocks and realize a goid thing when divines and patrons come with deals.
But it would not be devotion, imo, as much as barter.
Remember how Conan told Crom if Crom couldnt help then to hell with him?
Same thing IMO for LF cleric or warlocks.
As a GM i would approach LF PCs are what i call frontgrounded - not driven by long complex background but ready to react to upcoming events - their story is beginning, not already underway. They have very direct responses, so that should not be tough.
As for exploring their religions, i would look at it from what the divines and patrons want from the deal - as the LF is the more direct drive.
Finally, if i wanted to push a more long term drive, a guiding principle, i might push into LF play the competition for reproduction... Making "survival of fittest" and " breeding by fittests" their primary driver - so the adventuring might be driven by need to impress potential mates by glory and power acquisitions.
Tyr Anastasi of Andromeda, but without the higher education and philosophy, is a model, but there are tons of them in the various fantasy, scifi and even real world lore.
Just some ideas...