This package is very useful. I use it to run youtube-dl and attach to my irssi container. I do lots from irssi/termux; tweet slack irc. The termux-url handler is great as well. You can process shared urls from your browser based on their domain name. For some urls I pass them to youtube-dl for others I push to getpocket and a couple of other special cases I have as well. My tablet wouldn't be the same without it.
Using HTTP for 'apt update' is common practice. Neither Debian or Ubuntu use https for their repositories. Instead the metadata for each repository is signed with a gpg key. The associated public key is distributed with the installation media and used to verify the metadata. The metadata includes checksums for the other files in the repository. Debian and Ubuntu include MD5, SHA-1 and SHA-256 checksums. Termux includes just the SHA-256 checksums. These checksums are used to verify the integrity of the other files in the repository.