Juhani Otso Berg vs Kylo Ren: who would win?

Kylo Ren favored — Slight edge (~55%)

Juhani Otso Berg · Assassin's Creed · Base

Tier
9-A, up to 8-A
Attack Potency
Small Building Level+, up to Multi-City Block Level
Speed
Subsonic+, up to Supersonic+
Durability
Small Building Level+

Kylo Ren · Star Wars · Pre-Rise of Skywalker

Tier
9-A, up to 7-B
Attack Potency
Small Building Level, up to City Level+
Speed
Relativistic+
Durability
Small Building Level, up to City Level+

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.