There are two points here. Imposter syndrome and being an introvert.
First I'll cover the introversion. I'll be blunt and say I don't think this should interfere with interviewing in any significant way. I'm a massive introvert (that is someone who is massively introverted, not someone who is massive and introverted), and I haven't found this a negative. I think introversion is a fairly common trait amongst developers, so many introverts must succeed at interviewing. All being an introvert means is that you draw energy from solitude, whereas extroverts draw it from other people.
As in introvert you may have less experience talking to people. If you think this effects your interview performance, write out some practice questions that require a verbal answer and practice answering them out loud. Record this and listen back, you'll notice any problems with your speech qucikly by doing this.
Now for the imposter syndrome part. I think this is 100% down to mindset, and I'm going to tell you what I think the correct mindset to handle this is by telling you a story.
Impostor syndrome (also known as impostor phenomenon, impostorism, fraud syndrome or the impostor experience) is a psychological pattern in which one doubts one's accomplishments and has a persistent internalized fear of being exposed as a "fraud".
A short story by a senior developer
Early in my career I had imposter syndrome. I was worried about getting jobs that seemed too good, or paid too much. I thought I would get a job I couldn't actually do, and end up getting fired. This actually led to me not becoming a senior as early in my career as I should have. Around this time I was talking to an old school friend in London about a friend if his who had just got a really high paying accountant job at a major London company. The job almost doubled this guys salary, and jumped him up a couple of rungs on the ladder in one fell swoop. I was impressed, and mindful that I wanted my own career to progress faster, asked how his friend had acheived this.
Turned out he simply applied for a much higher position than he had before. Talked up his abilities, but not quite to the point of lying. Essentially he got it because he went for it and did a good interview.
I asked my friend, isn't he worried about getting fired? What happens if he gets there and can't do the job because it's too big a jump?
My friend said none of that was a worry. If he couldn't do the job, well that was the company's fault for hiring him. he didn't lie in the interview, and it's their job to make sure he can do the job before hiring him. The worst case scenario probably wouldn't happen as they'd give him a chance to upskill before firing, and even if he did, he could still then get a position higher than his current one just by saying he aimed high in getting the job he was fired from, but wasn't quite ready. Most people respect ambition.
My takeaway from that was to go for whatever job I wanted. It was up to their recruitment process to reject me if I wasn't capable of doing the role. There was no point in me deciding I wasn't good enough for the role - that was up to them and that was the company's job. This led to the mindset shift to, "If I get it, that means I must be good enough for it, if I'm not good enough I just won't get it, so onto the next interview".
A sense of abundance and freedom from outcome are key.text in italic