Helping one person, one time
You do not have to be accredited to help one claimant with one claim. Here is that door, in the regulation's own words.
One person, one claim
Any person may be authorized to prepare, present, and prosecute one claim (38 CFR 14.630(a)).
You and the claimant file VA Form 21-22a together, with a statement signed by you both that no compensation will be charged or paid (38 CFR 14.630(a)).
Once means once, and free means free
This authorization is good one time only; VA's General Counsel may allow an exception in unusual circumstances (38 CFR 14.630(b)).
No fee, ever: only accredited agents and attorneys may receive fees (38 CFR 14.636(b)).
None of these fit?
A bank or trust company acting as a claimant's guardian may appear through its own officer or employee, acting in its fiduciary capacity (38 CFR 14.634).
A legal intern, law student or certified paralegal is never independently accredited under that rule: they assist under the direct supervision of the attorney of record, with the claimant's written consent (38 CFR 14.629(c)(3)).
Anything rarer than that deserves a person, not a website.