I haven't been back to Lightbox since re-open but I would recommend considering a different style ear plugs like these ones meant for concerts:
https://www.amazon.ca/gp/product/B00G0PPTAK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Will probably give you a better viewing experience. They have different size ones (different colours are different sizes) so see what size you need or take a look at some other reusable ear plugs which will give you better audio vs foam plugs).
You will need a phone with a FM receiver chip. No iPhones have the chip, but some android phones have a FM receiver chip. You can then use an app like NextRadio Free Live FM Radio and tune the app to the drive-in broadcast frequency.