This company has deep underlying strength — its R&D capability is formidable.
Tips
culture
In martial arts theory, 内功 contrasts with 外功 (external, focused on muscle/bone/strength). Internal schools (内家拳) like 太极拳, 八卦掌, 形意拳 emphasize qi circulation; external schools (外家拳) like Shaolin emphasize physical power.
usage
Metaphorical use is very common in business writing: '一家公司的内功' = a company's underlying fundamentals (tech, talent, processes) vs. flashy marketing.