My arch linux with KDE only uses 500Mb ram after boot and I have a handfull of apps in the autostart. So I would guess with some explicitly lighter desktop environment you can be well below 100Mb
If you have a chance to add an ssd or nvme you could allocate a decently sized swap partition and let the OS handle the rest.
Maybe you won't be able to watch full HD youtube in big fat chrome browser, but otherwise it should work just fine I think.
It's no campaign. There is just a lot more (percentage wise) unfiltered trash on there.