Yes!!!
And neither one of us knows for sure. The only solid example of suicide we have is Judas killing himself over guilt of betrayal. It is significant to say the Bible does not record him as having ever repented. The argument probably needs to be over repentance, not suicide. I don't know....
We also have the example of King Saul. :)
1 Samuel 31:4 - Then said Saul unto his armourbearer, Draw thy sword, and thrust me through therewith; lest these uncircumcised come and thrust me through, and abuse me. But his armourbearer would not; for he was sore afraid. Therefore Saul took a sword, and fell upon it.
But then we see in 1 Chronicles the following:
1 Chronicles 10:14 And enquired not of the LORD: therefore he slew him, and turned the kingdom unto David the son of Jesse.
However, when Saul had him conjured up, Samuel told Saul that tomorrow Saul and his sons would be with him (1 Samuel 28:19).
So, God killed Saul for his disobedience via “suicide” but didn’t condemn him to hell for it.
Only the sin of unbelief is unforgivable.