The Lions play their final pre-series tour game against an Australia/New Zealand invitational side on Saturday, before taking on the Wallabies in the first Test on 19 July.
Toulouse’s progress to the Top 14 final delayed Kinghorn’s arrival on tour, and he lasted only 24 minutes on his Lions debut against the Brumbies before being replaced.
England’s Marcus Smith, whose ability to cover both fly-half and full-back was key to his selection in the squad, has played the most minutes at 15, with Tommy Freeman, Mack Hansen and Huw Jones also able to fill in if the Lions find themselves short.
Lions head coach Andy Farrell gave Osborne the first of his eight Test caps at full-back against South Africa last summer, but the 23-year-old is more used to playing in midfield.
Scotland’s Tom Jordan and Wales’ Blair Murray might also have entered Farrell’s thinking as options to cover for Kinghorn.
