As an EA with political organizing experience I think EA has plenty to say to your friend. Money is useful as a unit of analysis because it’s quantifiable and fungible, but the same analytical framework can easily apply to donations of time, with the caveats that 1) Donating time will vary a lot more in its value depending on the specific service one performs and it becomes a lot more important to pick the right volunteer activity in addition to the right cause, 2) there will be some causes or organizations where it is not possible to donate time effectively, so the highest-value intervention might be different.
Being politically experienced, I would think your friend already has an idea of the highest-value services they would perform for a candidate or organization, although in some cases the highest-value candidates/organizations may have no need for those specific skills, so there could be a tradeoff between doing a more useful activity for a less impactful candidate/org vs. a less useful activity for a higher-impact candidate/org. But if you have a sense of the marginal values of different activities that should be easy to quantify, and then you can assess how high-impact the candidate/org is. For the latter as applied to the Presidential race, see the Candidate Scoring system at https://onedrive.live.com/?authkey=%21AMwfqLPOC5Rim5E&cid=E49A0797F8708ADD&id=E49A0797F8708ADD%217949&parId=E49A0797F8708ADD%217946&o=OneUp. For a better example of the former analysis than most political people seem to have done, I recommend Graber and Green’s Get Out The Vote, with 2 caveats: 1) it focuses only on turnout, and persuasion may be different; 2) the effects that seem to be the strongest are under-studied because political scientists seem to have a fetish for grassroot-y stuff over mass media. https://www.amazon.com/Get-Out-Vote-Increase-Turnout/dp/0815732686. If your friend needs help with the quantitative analysis of these tradeoffs I’m happy to help.
I donated the legal max to Cory Booker and am now donating what I can afford to the DNC, in case you’re wondering where I personally come out on this.