giffgaff / o2 delivery reports are non standard and work by prepending *0# to the start of each message. so far only evolvesms has this option.
Can Textra get this added as its been requested since 2014 and nothing has been added. i know its a very specific feature for this network but its has over 23 million customers on this network. So many potential customers are missing out.

With over 23 million customers, O2 runs 2G, 3G, 4G and 5G networks across the UK, as well as operating O2 Wifi and owning half of Tesco Mobile. O2 has over 450 retail stores and sponsors The O2, O2 Academy venues and the England rugby team.

if this could be added to the PRO version would be a good selling point for the app and surely get you more sales / customers!