True, I haven't been able to ride it much lately, but the bike has over ten thousand (maybe approaching 20?) miles on it (was my commuter for many years.) The chain is fully enclosed, and I live in the San Diego area, a few miles from the coast, so we're just far enough from the sea air.

Still though that is a lot of miles for a single chain so I would have to imagine it would need to be replaced. Being it is fully enclosed it probably sees even less maintenance (which yes granted it will require a little less depending on how well sealed it is). I would be quite surprised if it wasn't worn out.

I've cleaned and lubed it maybe half a dozen times (which is a PITA, because you have to remove the encasement). Each time I was surprised at how clean it still was.
I used to go through 2-3 chains per year on my road bikes (and I was Q-tip and Tri-Flow diligent weekly). It's pretty amazing how much road grit the front tire throws on the chain, and how damaging it is.

You are unique most of the folks who have those types of bikes never touch them because those covers are a huge pain. I am with you there. It does help though but in the end you are still riding and wearing material.

It's not your typical 10+ speed chain. It's quite robust, like the chains we used to have on our BMX bikes when we were kids. And the Sturmy-Archer IGH means no exposed, wimpy aluminium gears. Them Dutch have crappy, British weather and they know their bikes.
And despite being such a flat country, I believe the Dutch might still hold the record for the most stage wins on Alpe d'Huez, (though probably not on opafiets like this.)

When I think of Dutch bikes these days this is what comes to mind. It’s Swiss designed but I’ve ridden them and they are really cool.

Oh I know, I know but still even that still is a chain and still needs maintenance and replacement and a 10+ speed chain is also quite robust as well.

This bike was "free" in the local buy&sell, a nice young German couple were emigrating and couldn't get rid of it - it was badly neglected, rusty with cobwebs, nothing worked but nothing was frozen in place, so I stripped it down and rebuilt it all, even completely overhauling the Sachs Torpedo 3-speed rear integrated hub.

I really like it, but as per usual I'm maybe the only person who sees the value in it. The bike is just slightly too small for me, but I'm 185cm so it's slightly too big for most cyclists in Ireland.

What are people's thoughts on converting it to an e-bike, using a front wheel kit? The installation of it would be easy, a thumb throttle on a front wheel motor, the battery on the rear rack and controller on the seat tube. Has anyone here done this? What's it like to use? Probably a lot easier, as it's so heavy that getting going is the hard part; once moving the bike is lovely.

But would I be ruining it by doing this? If it's not valued anyway, what's the harm (other than I'm just paying for the experience of the conversion, and will never get that money back).

Ride it as is, the bike is not suitable for an e-bike the brakes are nearly non-existent (spoon brake at the front?) and the frame is probably not going to be strong enough to handle the torque. If you want an electric moped get one, plenty of options same thing with e-bikes plenty of great options including actual dutch bikes from Royal Dutch Gazelle and they use reliable Bosch motors and are well built and are one of the oldest bike manufacturers as well. It is a neat bike but certainly not a good candidate for converting to an e-moped or e-bike.

The left one. Obviously

Yeah, that's a big downside, the lack of brakes LOL. I figured a front wheel motor would be easy, balancing out the rear weight of the bike, and the impact on the frame would be negligible.

Thanks for being a "voice of reason", confirming any conversion here would ruin an otherwise nice little bike, and it'd just cost money I could spend on tacos.

Tacos are better : )

Sorry, I scrolled through the posts without much attention, except for "Dutch".

How about taking a look at Pon Bike, the Dutch company that owns many brands.

https://pon.bike/brands