web-based apps/progressive web apps developer

Do you want to help seniors live a longer, higher quality life and help the environment at the same time? Bay Area Older Adults is a charitable 501(c)3 organization that improves the health and well-being of seniors in the Bay Area. The organization is managed by volunteers and this is an unpaid part-time volunteer position. We are looking for someone with expertise in web-based apps/progressive web apps to help us complete development of an app we built for helping people with disabilities. We want to be able to use the app where there is no data and still show YouTube videos and play server-stored mp3 files. Thank you for your consideration.