Here is okay still - probably a good place to discuss the desire/need for graph functionality more generally anyway 
I’m not fully in context to reason about it right now, but I believe bread-first search (BFS) more or less respects how SQL executes anyway, and without recursive CTEs it can generally be achieved using multiple explicit CTEs (one per depth layer), e.g. play
However, for now though I think depth-first search (DFS) using v2 would be blocked on the lack of recursive CTE support: Support CTEs, §7.13 · Issue #2087 · xtdb/xtdb · GitHub (both internally and in the SQL grammar) - though you can of course run multiple queries, and system_time at least gives you a stable/consistent basis for doing so (even if it’s not as efficient as pushing it down into the database properly)