Ex partner is uncontactable - Unable to divorce

I'm going to change names here to Siobhan and John.

Siobhan was in a relationship with John for 10 years and married him after 8.5 years together. From the start, Siobhan was a deeply caring and supportive partner. She knew John used drugs occasionally, but she didn’t realize how serious his addiction was until after they got married.

Once married, it became impossible to ignore. When Siobhan confronted him about his drug use, John never admitted to it. He would deny everything, gaslighting her, claiming drugs left around the house were “flour from cooking” or that drug dealers she saw him with were just friends. Despite clear evidence, he refused to take admit anything or responsibility. She really wanted the relationship to work so she just let things go, which is what John was pushing for, to just wiggle out of an argument.

John’s avoidant behavior went far beyond the drug use. When he lost his job for too many absent days, instead of being honest with Siobhan, he pretended to go to work each day but actually slept in his car. Siobhan worked tirelessly to support him, covering all their expenses, rent, groceries, car insurance, and more. She even arranged and paid for counseling sessions in the hope that he’d get help. He promised he attended them, but he didn’t.

The situation reached a breaking point when drug dealers showed up at Siobhan’s family home, demanding payment. It was a complete shock to her family and Siobhan was extremally embarrassed and was furious with John for bringing it so close to home, involving her parents, who had to scramble to take out loans to pay off John’s debts. Siobhan, who already carried most of the financial burden, was devastated but still tried to help him. Even after all this, she gave him one last chance, but six months later, she had a reliable friend who seen John making another drug deal with the same dealer he’d sworn to avoid. When confronted, John denied everything yet again, leaving Siobhan overwhelmed with stress and anxiety. She finally asked him to leave.

After he left, John went to stay with his father but was eventually asked to leave for continuing to use drugs. He’s now in a homeless shelter and is completely uncontactable. John has no phone, no email, and no social media. Even when family members have tried to meet him, he’s avoided them, standing them up. Even early on, at the start of their relations, John wouldn't use a mobile phone much. He always said he has no need and his phone would just be left on a counter top with a dead battery.

The Current Problem:
Siobhan has been separated from John for a year and a half and wants to finalize the divorce so she can move forward with her life. She initially consulted a solicitor but was quoted €15,000–€30,000, which she just can’t afford. Although she earns just over the free legal aid threshold, she doesn’t qualify for assistance, leaving her in a tough financial position while she’s still repaying the loans taken out to cover John’s debts.

Mediation seemed like a more affordable option, but it requires both parties to attend and sign documents. Given John’s extreme avoidant behavior and the fact that he’s unreachable, it’s nearly impossible to get him to show up, even if Siobhan arranged transport for him. It's not that John doesn't want a divorce, it is genuinely that he is uncontactable. The rare times when his sister bumped into him, he said he contact Siobhan but it just never happened.

When Siobhan was in contact with the solicitor, he advised that the legal route could eventually allow a judge to grant the divorce without John’s involvement, but this would cost thousands of euro, which isn’t viable for Siobhan.

Siobhan gave everything to this relationship. She supported John emotionally, financially, and in every other way possible, even at great personal cost. All she wants now is to close this painful chapter of her life and move forward.

My Question for boards.ie:
Has anyone been through a similar situation or know what options Siobhan might have to finalize the divorce under these circumstances? Are there legal or alternative routes that might work when the other party is completely uncooperative and unreachable? Any advice or insights would mean so much to her.