This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
勴 combines 慮 (thought, consideration) and 力 (strength, effort). The exact historical development is uncertain, but it likely relates to helping or exerting effort with thought.
The left side 慮 suggests careful thought, and the right side 力 adds strength. Together they hint at helping through thoughtful effort, but the exact meaning is unclear.
For リョ, imagine a thoughtful person named Ryo lending strength to help: Ryo -> リョ.