No true! It is actively *maintained*, I'm just unlikely to add new features without sufficient motivation at this point (maintenance ≠ feature development). ;-)
(Obviously I will accept patches for any of the requested features, so feel free donate your time if money isn't available to you!)

Thank you for your review! The “huge cache of hundreds (!!!) of files […], which may be completely removed” are in fact used to generate sensible values for the `navigator.*` browser identification values. Parsing information like operating system, CPU type, device type, … is not a simple affair as there are no standards at all – one just has to guess based on the COMMENT parts of the User-Agent string. Fortunately the BrowsCap project has maintained a list of matching patterns for figuring out this information since 1997 that is extremely reliable. As such, I will continue using it even if it means bloating the extension size by about 3MiB. The fact that it allows everything to just work out-of-the-box with just a single input value (the User-Agent string itself) definitely outweighs that, by comparison small, price.
I would like to think that, if you don't need this complete level of emulation, then you may use just about any of the other User-Agent switching extensions because – to my knowledge this capability is unique to this extension.
- Alexander

Thank you for your review! Unfortunately a Chrome version of this extension is not planned. You can find my full reply to this, as well as donation link for making this feature happen, at this link: https://gitlab.com/ntninja/user-agent-switcher/issues/46#note_166783499

=============== Simplified Portuguese translation ===============

Obrigado pela sua opinião! Não está prevista uma versão cromada desta extensão. A minha resposta completa pode ser lida aqui (Inglês): https://gitlab.com/ntninja/user-agent-switcher/issues/46#note_166783499 (Também tem um link de doação.)

Thanks for the nice comment! :-)

Sorry. I'm not familiar with Indonesian/Malay. Do you see a black screen? Du you see a permission error? Please write short and simple sentences. This will make translation work better.

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Maaf. Saya tidak terbiasa dengan bahasa Indonesia / Melayu. Apakah Anda melihat layar hitam? Apakah Anda melihat kesalahan izin? Tolong tulis kalimat pendek dan sederhana. Ini akan membuat penerjemahan bekerja lebih baik.

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Maaf. Saya tidak biasa dengan bahasa Indonesia / Melayu. Adakah anda melihat skrin hitam? Du anda melihat ralat kebenaran? Sila tulis ayat pendek dan mudah. Ini akan menjadikan kerja penterjemahan lebih baik.