Thank you! I hope that somebody else would know something more.

Another thing I sometimes find irritating is when collectors claim that poorly documented examples of lamps and lighting equipment do not exist or when collectors say that information in technical documents is incorrect even when I try to share my proof citing the technical documents I found my information from and they get defensive and tell me that I am wrong even if I tell them where to find the information.

Yup, so you should be good on from the OCV perspective, I am sure someone else can chime in later about the potential 16% underdrive and whether or not that is gonna cause a problem.

My high school (built in the early 80s) used originally all 40W T12's with Prusman (Germany) metal can starters, no thermal cutout whatsoever

The starters were rarely replaced, they were kept many T12 and T8 tubes later. They would become progressively slow over the years, with some starters taking 20..30 seconds from switch on until any heating of cathodes / blink / sound from starter starts. But when they started, it was one long (5+ seconds glow in the ends of the tube) preheat and start at once, without blinking. So even when so old, they were still gentle on the tubes

I made Some research and discovered that 90w lps runs on 112v and 80w me runs in 115v but a bit lower current than 90w Sox. 18w Sox start up very well with s10 starter and 18w t8 ballast.

Ehh, I would say good enough for short term. My semi-accurate calculations predict ~16% underdrive. I am not familiar with how LPS tolerates underdrive so I have no idea if this is acceptable or not. Also the lamp might not stay struck, as 230VOC is kinda low for a 112V arc lamp, especially with something as high power factor as LPS.

If the ballast has different voltage taps on the input (220, 230, 240), use a lower one than normal to maybe get a little more current out of it. I don't think you will severely damage the lamp, but I don't guarantee it will actually work.

Edit: Nevermind, I just looked it up and it appears that ~230V choke ballasts do exist for LPS. It should stay struck just fine, just probably underdriven.

Good glow starters in fact last a lot. And probably can outlast a few tubes if not abused by constantly blinking an EOL tube. BTW, at home there is a better possibility someone will notice an EOL tube timely and turn it off and replace quickly.

The problem is the starter gets overheated when the tube is degrading so the starter "just not trips yet". Problem is, the dissipation builds slowly and so does the starter temperature. But unlike during normal start (when the electrodes heat up so quickly the way more massive bulb stays cold before the lamp starts and the starter stops dissipating), with a worn out tube the thermal loading stays for rather long time, so the theat has plenty of time spreading over the whole starter bulb, so the whole thing gets very hot, All that while the fluorescent still appear lighting normally.
If the glowbottle is supposed to last long, there would need to be some kind of thermal cutout, responding to the starter bulb getting hot. That way the heat stress is stopped before that much excessive wear, so the starter then can last multiple bulbs. This is used in the classic format safety starters, which then are rated to last at least 3..5 lamps. But that cutout mechabism reliability is another can of worms, often failing on its own due to contact oxidation,.. But that would be way too expensive for such cheepeese products. Even with normal fluorescents the extra life of the curout starter won't cover the higher price, so they are used virtually only when there is another justification for them (like stopping the EOL lamp flashing,...).

Would 80w mercury ballast work? (230v) if doesnt then i might be bit screwd.

Some have had success with the short-it-out method. Using a switch (or a very durable fluorescent starter) just short out the ballast momentarily to get the inductive flyback pulse, that should strike it. With the proper ballast of course.

I’m getting 7 pcs of 90w sox lamps and i dont have ignitor for these. I only need one but i was thinking that would there be anything else way to start those lamps?  Here in Finland all sox light has been removed 10-15 years ago so it very hard to get gear for those.