I've needed to transfer files between an iOS device and an Android device pretty regularly lately and it's simply impossible, I've literally been waiting months

I've needed to transfer files between an iOS device and an Android device pretty regularly lately and it's simply impossible, I've literally been waiting months to transfer a few files because the person who has the files has an iPhone and has difficulty using any method other than Airdrop (e.g. Dropbox.) Which I view to be an intentional design decision by Apple. WiFi direct would be fine, Airdrop is proprietary and useless here.