Turning a beer into a sour or funky beer

[The_Glue]

I have a beer which i brewed about a year ago. I've seen something which looked like a pellicle on the top of the beer 2 weeks into the fermentation.
I left it in the primary since then. The pellicle was a false alarm probably, it is not sour, pellicles disappeared. Headspace is quite big, plastic bucket.
The wort was a single base malt 30 ibu APAish light beer.

I thought that instead of dumping it i could pitch something wild into it maybe.
What is better, lacto or brett in this case? (big headspace, possibility of picking up oxygen)

(btw i can't really buy liquid yeast here but i have access to Orval and various lambics to get dregs from and also have acid malt (not sure if it is useful), i am even open to catching some wild yeast, i have access to a wine cellar (with all kinds of mold) and a vineyard)

 

[Oldsock]

I think lambic dregs would be the best option if it doesn't taste terrible already. Any way to move the beer to a carboy? You're luckily that the lid was attached well, that's usually the biggest issue with buckets. Headspace isn't a big concern, because unlike barrels. being dry doesn't increase the permeability of plastic.