I use the VLC iPhone/iPad app to transfer files. There is an option to show the files on your iPhone/iPad as a webserver which works on any device that has a browser (you have to be on the same network).
Fair warning about this method: It will transfer the file just fine, it is depending on iPadOS recognizing there is a file somewhere else. If you are using it for watching video files, you will have to use VLC since iPad video app will not see the file. I tried to use the iPad to watch my video collection (Plex and Emby required paid app for streaming to the iPad), it does weird thing with them. Some of the video file (in MKV, encoded with various format [x264 and HEVC]) will load the video just fine, it will have problem seeking and missing subs (it is already in the container), dropped audios and stuff. I thought my video files is the problem and i tested them in PC and my Note 8, it ran just fine. I would believe it is something to do with iPad OS, PC and Android VLC played the video without issues.
