Even if you make just the venue number-one in Japan, if the content is third-rate, what's the point, right?
Literal
No-matter-how vessel only [obj-を] Japan-best [to-に] do-[even-ても], contents [subj-が] third-rate [copula-やったら] no meaning [not-ない] [question-ちゃうの]?
器だけを日本一にしても 'even if you make only the vessel/container the best in Japan' uses 器 metaphorically for the outer/physical aspect versus 中身 'contents/substance.' やったら is the Kansai dialect past conditional of だ. な~ん is a dialectal emphatic negator. ~ちゃうの is Kansai-feminine questioning. A criticism of prioritizing appearance over substance.