During the recent 10-day Spanish training camp, Thompson appeared as a substitute for the injured Izale McLeod in a friendly against Brighton – and scored.
The teenager converted Lloyd Sam’s right-wing cross from close range on the stroke of half-time, although Appleton’s men went on to lose 5-1.
Days earlier, he came on as a second-half substitute in the 4-0 defeat against Gibraltar.
The Blues’ next friendly is at Aldershot on Wednesday night where a bumper away following is expected.
Around 70 Pompey fans witnessed Thompson netting against Brighton at the Barcelo Montecastillo Resort.
And the Academy graduate is hoping to continue making an impact in his bid to prove his worth.
He said: ‘It was a great experience to play Brighton and also Gibraltar. It has been good to be in and around the first-team set up with the gaffer and coaching staff.
‘The gaffer told me to come on and do a job against Brighton and it was a good feeling to score.
‘Lloyd (Sam) put a good ball into the box and I tried to get on the end of it, get ahead of the defender and I did and got good contact and it went in.
‘I went in front of the defender and then pulled back off to get away from the marker to get contact with the ball, so it was a bit of movement as well.
‘To be fair, in training I have scored a few like that, so it has been good to get off the mark.
‘I scored for the Academy against Ipswich on my debut which was similar, I got across my man with a diving header.
‘That Brighton goal has been a massive confidence booster for the season ahead. If I do stay or if I go out on loan it gives me confidence that I can get goals and do well if given the chance.
‘Even in training the next day, I felt much more comfortable on the ball and much more confident. It does give you a big boost when you do get off the mark, even though the result was not great.
‘I’ve got to keep working hard, keep training and keep concentrating, you never know what can happen.
‘Hopefully if all goes well I might get a few more during the pre-season.’
Thompson made 12 appearances on loan at the Hawks last year, although started just two of them.
He also failed to score in what would prove to be a stay hampered by an ankle injury.
Now he is part of the Pompey development squad after penning a one-year deal this summer.
And he’s relishing the campaign ahead. He added: ‘My aim this season is to get into the first-team squad. I am not sure if that is possible at the moment, it is down to the gaffer if he thinks I am ready or not.
‘But wherever I’ll be – whether it is the development squad, first team or on loan – I will work hard, put in 100 per cent and see what happens.
‘It’s about what the gaffer feels it is right, then I will do it and hopefully get goals wherever I go.’