Is there warranty on Lightning to 3.5mm headphone jack?

Yes, 1 year. This warranty excludes damage resulting from abuse, accident, modifications or other causes that are not defects in materials and workmanship.

See this:--> Your Hardware Warranty

Regards

Giulio

Same as all Apple accessories. 1 Year from the date of purchase from Apple or an Apple Authorized reseller.

Link-> Legal - Accessory Warranty English - Apple

My pleasure

Since they are not in production any longer, you might try finding them at an e-commerce online website, or any Apple Store which can have them in stock.

Ahhh, 2nd generation Airpods should be still available.

I don't own Airpods, but a friend of mind has the 3rd generation model and he's totally satisfied.

:)