install openssl-tools then use add-trusted-certificate against the .crt file, so curl will work fine (still not for elinks, i wonder why that works on macos and linux, or maybe not? just use playwright instead.)
chromebook is different. you need to export the proxy to 0.0.0.0 by means of nginx or something, so you can configure proxy to 100.115.92.14 or 100.115.92.2 as seen in termux by ifconfig