Both jacking points on the driver's side of a W201 190model.

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I had a very similar rust problem on my old 450SE. You are probably looking at the proverbial 'tip-of-the-iceberg' here. There is an internal bracing structure inside the rocker panel that allows the weight of the car to bear on the 'pipes' that you insert the jack into, which are covered by those rubber caps. The rust-out evident in the pictures may be accompanied by internal rusting of this bearing structure. Any attempt to jack up the car using these will likely bend the pipes upward, and they may or may not hold up under the weight.

OK, so on to your question: It would be very expensive to rebuild the internal bracing to restore the jackpoints to functionality, if there is a lot of internal rusting, because the repair would entail cutting away both inner and outer rocker areas to access the damage and retrofit new bracing, plus attendant finishing work.

On the other hand, if the internal bracing is intact (and it may well be), fitting a new 'skin' around the rusted pipes would be quite inexpensive, if cosmetics is the main concern. Somewhere in the middle would be replacement of the entire outer rocker panel with a premade patch panel. (I did one side in the driveway, starting with cutting out the old and fitting the new, welding and bodyfill, sand prime and finish paint, in about 7 hours, but a bodyshop wouldn't work nearly that fast.)

Try putting the jack into the hole and slowly see how the structure bears up while the car is lifted. Stop at the first sign of the pipe bending upward. If you raise the car off the ground with no evident bending, you're in luck and can probably get away with a simple (inexpensive) patch around the rusted skin areas. If you can weld, it's about a 5 hour job on each side, total.

PS: On my old 450SE, it wasn't worth a proper fix, so I went the cosmetic route and used a scissors jack instead of the stock set-up.

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1986 560SL
2002 Toyota Camry
1993 Lexus

Yep. That's kinda what i was thinking. Wondering if there was a premade patch panel that could replace the entire outer rocker panel. And then I'd just use a scissors jack at some other location if need be. A "cosmetic repair" as you mentioned. But then I'd be concerned about the rust that I left underneath the new panel; in that support structure. It might continue to grow and spread.
With the extent of rust in these two spots, I'm wondering if I should be overly concerned about other rust in other locations of this car. (Only the driver's side jacking points were mentioned.)

Typically, those rockers rust from the inside out. Water gets in from sunroof drains, holes in the inner panel area, and especially from water/snow/salt (in my area in winter) getting driven at the area in the front wheel arch just behind the wheel. On some models, there's a plastic guard over a hollow space in the rear of the front wheel well used to house a vacuum canister. Holes start small and once they open up the rocker 'cylinder', it's just a matter of time until rust surfaces, as in a decayed tooth. Also, the rockers are a vital part of the structural integrity of the car, so extensive rust is really a problem, since the steel is not designed for high heat welding (although a MIG welder used properly does work).

I sourced an aftermarket patch panel, made in Mexico, from UAP I think, that worked for me, and was cheap ($75.00 CDN as I recall), but that was for a car that was on its last legs and I only needed to run it for a couple of years more.

You'll need to make a judgement call on all of this, but if the damage is mostly what's shown in the pictures, and you didn't care about using the stock jack, I'd get out the tin snips and scrap metal and form my own patch pieces. Low-end finishing would be with pop rivets and bondo. High end would be welded solid, surface filled, then prep and recoat the entire rocker with 'rock guard' and finish paint.

__________________
1986 560SL
2002 Toyota Camry
1993 Lexus