There are few things to look for and it all depends on what bike you want.
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derailleurs and shifters: With friction shifting you can slap any derailleur on bike and it will work. Otherwise look at the brand, model and number of speeds, they can have different cable pull standard that isn’t in production.
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bottom bracket: It is mess of different standards but it shouldn’t be problem sourcing replacements.
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frame: Good steel frame will outlive all the other components, so look at the mounting points for them. Flat mount disc brakes or type of V brakes, BB diameter and type,…
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fork: Go for rigid fork if you want less things to worry about.
Basically look for all the parts, how to buy them, change them, if they require special tools…
If you really need/want to, use foreign coverage of it. Maybe BBC or other English world wide news will have something (DW, 24France).
You will get mostly unbiased info and it is usually more chill than the heated debates. I use this sometimes but for my country it doesn’t cover much news.