Why would you pay for such feature ? Termux is basically a small Linux in your pocket and has anything you'd ever need regarding SSH
It's far quicker and easier to hit a toggle in JuiceSSH to turn on a port forward than to open up termux and type in the commands.
JuiceSSH was popular starting 2013-2014 and Termux was released in 2015. ConnectBot technically existed before but its keyboard has always left more to be desired.