There are two comments to make about the composition of "the disciples" as recorded by John 20:22
We know that whatever "disciples" means it does NOT mean (at this point) "the eleven" precisely because Thomas was absent as recorded in John 20:24.
The word "disciple" is translated from the Greek, μαθητής (mathétés) = pupil, student, one who is associated with learning from a master (Christ in this case) who shares the views and practices of the master (BDAG).
It means more than just "the twelve" or "the eleven" for the following reasons
- In Matt 28:19, Jesus specifically instructs the disciples to make more disciples
- Luke 6:17 describes a large crowd of Jesus disciples
- Luke 19:37 also describes a large multitude of disciples
- John 6:66 also appears to be the same usage
Thus, "disciple" appears to mean any believer/adherent of Jesus, whether male of female which applied after Jesus' death and resurrection:
- Acts 6:1 - In those days when the disciples were increasing in number, the Grecian Jews among them began to grumble against the Hebraic Jews because their widows were being overlooked in the daily distribution of food.
- Acts 6:7 - So the word of God continued to spread. The number of disciples in Jerusalem grew rapidly, and a great number of priests became obedient to the faith.
- Acts 9:1 - Meanwhile, Saul was still breathing out murderous threats against the disciples of the Lord. He approached the high priest
- Acts 9:10 - In Damascus there was a disciple named Ananias.
- Acts 9:19 - and after taking some food, he regained his strength. And he spent several days with the disciples in Damascus.
- Acts 11:26 - and when he found him, he brought him back to Antioch. So for a full year they met together with the church and taught large numbers of people. The disciples were first called Christians at Antioch. [Note that at this point, most of the original eleven were still in Jerusalem.]
- Acts 11:29 - So the disciples, each according to his ability, decided to send relief to the brothers living in Judea.
- Acts 13:52 - And the disciples were filled with joy and with the Holy Spirit. [This appears to refer to Paul and Barnabas.]
- Acts 15:10 - Now then, why do you test God by placing on the necks of the disciples a yoke that neither we nor our fathers have been able to bear? [This refers to all Christians.]
- Acts 21:16 - Some of the disciples from Caesarea accompanied us, and they took us to stay at the home of Mnason the Cypriot, an early disciple.
In John 20:22, we are not told, at least in that verse, who composed the group. However, as pointed out by the OP, the parallel passage in Luke 24:36-49 says many people were there, including Cleopas (V18).