[SalesForce] How to pass two Id within URL using getParameters().put

The advantage with OOP languages is that, all the object assignments are references by nature. So even when they are passed via parameters, change in one method will reflect in another method when same reference is passed as parameter. To help explain this better, consider below example:

@future
public static void myFuture(List<Id> accIds){
    Map<Id,List<Contact>> accountsToConsMap = new Map<Id,List<Contact>>();
    met1(accIds, accountsToConsMap);
    met2(accountsToConsMap);
}

public static void met1(List<Id> ids, Map<Id,List<Contact>> accMap){
    List<Account> accs = [SELECT Id, Name, (SELECT Name FROM Contacts) FROM Account];
    for(Account acc: accs) {
        accMap.put(acc.Id, acc.Contacts);
    }
}

public static void met2(Map<Id,List<Contact>> accMap){
    System.debug('contacts map => '+accMap);
}

Here accMap acts as reference to accountsToConsMap, so although you modify it in met1 method, its value will reflect in met2 method also.

You can implement your logic in same way. There is no need to return anything in 1st or 2nd methods. Just pass parameters which acts as references and consume/process them in any method.

Wire methods don't fire on "undefined". You need to make it null instead:

inputDate = null;

Or, alternatively, set a specific date:

inputDate = new Date(new Date().setFullYear(new Date().getFullYear() - 2));

Note that the values you get are real dates, you don't need to Date.parse:

@AuraEnabled(cacheable=true)
public static List<Account> getAccountsToVerify(Date inputdate) {
  return [
    SELECT Id, Name, Outcome__c, Verification_Date__c
      FROM Account WHERE
      isPersonAccount = TRUE
      AND (Verification_Date__c = NULL
      OR Verification_Date__c < :inputdate)
    ORDER BY Name
  ];
}

Edit: I packaged this up for you, if you want a copy to work with.