We do have our own implementation of weakly connected components [1]. Currently, we only have NetworkX strongly connected components algorithm [2] as a part of the nxalg module (set of procedures) in MAGE (our graph algorithms library). I did not compare it yet, let me know if you do! We definitely need to create official benchmarks. Lot of work!
[1] https://memgraph.com/docs/mage/query-modules/cpp/weakly-conn...
[2] https://memgraph.com/docs/mage/query-modules/python/nxalg#st...