A pending eTA application is "irrelevant" when applying for admission at a land border. Pending eTA application in itself is not a problem. Many have opt for the land border route if they need to travel but forgot or did not know about the eTA requirement.
Some people have names that are unfortunately also associated with other people who are deemed undesirable or of interest by Canada (or another country sharing the many "blacklists"). If they show up on a land border and their other personal information (e.g. age, appearance, sex/gender etc.) clearly demonstrates that they are not the person of interest, they are likely to be granted entry (assuming other admission requirements are met or deemed met).
However, your vague description indicates that your application is more complex because there is reason to believe that you may be inadmissible into Canada based on your answer(s) to one of the questions on the application. This will be a problem.
For example, if you have a criminal record, you may be inadmissible depending on the seriousness of the crime, the time passed since the completion of any sentence, and if you have received a pardon or equivalent measures. Treatment of these cases can be long. The seriousness of crime for example is assessed based on the corresponding offence in Canadian law that your action may have constituted if the action were committed in Canada, which is not a straightforward procedure.
The officer processing your application on land border will have access to information you declared on the eTA application form. They are required to assess your admissibility based on the totality of your application and personal information known to IRCC.
They are likely to ask for similar documentations that may justify your admissibility or allow you to overcome inadmissibility.
In other words, going to a land border may allow you to "jump the queue" and get your admissibility assessed immediately instead of waiting for your eTA application to be processed. But the assessment will be done more hastily and it is unlikely you will be offered opportunity to gather needed documents if you do not have all demanded documents on hand. The officer is not required to give you the benefits of the doubt and you have the burden of proof.
