I was thinking about your question on my morning run. Many of the other responses focus only on ONE aspect of your question/situation. I was trying to think about it "from all sides".
Your question was "has anyone else reached FI and then taken a retail/low wage job for benefits/discounts" (Paraphrasing here...).
I'd answer that yes, I've taken low-wage work for benefits/discounts, in multiple ways...
Example, I work for free at local runs, that means I get to participate in them without paying.
I teach part time at local com college, so I can take other courses for free/get out of the house, help others obtain their goals.
I don't see this as a "single point" question (Do it just for the discount...).
I'd suggest there might be other benefits:
1. You get out of the house and get interaction with others. You mentioned that you can't travel (yet). I'm in the same boat, so getting out of the house for little adventures/meetings/church etc. is very valuable in ensuring I don't sit at home all day, watching netflix...
2. You'll be exposed to co-workers who can offer advice/suggestions on the projects you are planning. Getting the "inside scoop" from the old plumber working the plumbing section can be a great help. They can also tell you who to hire (if you need to hire out) and who to stay away from (lot's of half-ass contractors out there).
3. You'll be exposed to new skills and challenges. I was tired of my line of work and seeking new challenges, even if low skill etc, I was glad to find new roles to "try out" and see if they fit my aptitude/abilities etc. Something as simple as learning the floor layout, how to run a forklift, how to cut rope, they can all teach new things, especially if you are not coming from a hands on "line of work".
4. You might get some extra movement/exercise/fitness benefits out of the situation.
5. It's not THAT hard of work, my 18 year old has been working retail for two years... She's not a people person but she makes due, she has a lot of friends at her job and, being 18 years old, she'd rather be there than home... :)
6. As others have said, you can always walk away, you have FU money and are not in a wage slave situation. This makes you a VERY valuable employee. You'll likely add value to the organization as you are not scared to speak your mind but also smart enough to know what to bring to management and what falls under the umbrella of "that's just how things are in this org/line of work". I often ask questions that others are "scared" to ask, and they reach out to me later and thank me for asking the "hard" question that they wanted to ask but were afraid of looking dumb/being penalized for asking....
So, running it through multiple "filters" I'd say it's a fine idea. Best case, it's a "hobby with benefits" where you make new friends, support org leadership, and have other intangible bennies. Worst case, the leadership sucks, you can't stand the customer interactions, you don't like the work hours and you walk away.
Just my .2 cents.