I’ve been in the same boat for a while , OP. I tried an agency and tried hiring internally as well.

What I learnt was –
1. It’s important you have someone who understand the common search phrases or prompts your target audience would likely search. Whether it’s an agency or someone internal, both are fine , but an internal person is more likely to understand your audiences better. This also depends on the industry and your target audience, needless to say there should be a match between your offerings and target audience , else every effort is a waste.

2. Your website , social media and SEO are linked together. Make sure all 3 initiatives are running in the same direction with the goal of converging at one common point. Hence organisationally, having these 3 teams working together is ideal , else you are simply delaying the timeline for your desired SEO results.

3. SEO takes time, plan finances for atleast 2 years to see positive results. In the meantime , work on getting your basic SEO optimised website and social media accounts running , which is no small task either but a necessary pre requisite for a successful SEO campaign.

4. My solution was hiring a team for 3-5 people who will handle all these things for you , it will cost the same as an agency but the internal people will be in a better position to get things done as they understand your business and customers better , and don’t have multiple clients to work with. Ofc, they need to be technically sounds and preferably understand your industry well.

Only if you dont have the time or expertise to hire or filter people , then go for an agency but try your best to bridge above gaps.

Thanks and good luck!