With an aging population, there's a growing need for HCI solutions tailored to older adults. What design considerations should we take into account to create user-friendly and effective technologies for the elderly?

User testing, user testing, user testing…
Your design team should iterate with demo workflow to understand the fall out event in the desired experience. Regardless of an elderly audience or a gen Z, the product design team must test their designs proposal before going to coding

By HCI, I believe you mean Human-Computer Interaction, not Hyper-converged Infrastructure, the company, or some other HCI acronymn.  
I'm not sure there are design considerations for the elderly any more. Most older people have grown up in the computing era and know how to click and use a mouse. They know standard elements of a GUI, like menus and pop-ups.  They use apps regularly. It may be interesting to research this question to check your assumptions about the need.  Everyone likes easy to use solutions, not just older adults. Everyone wants an App-like experience.  Everyone wants AI to help.
That said, we all know that older adults tend to develop ailments that might mimic disabilities in younger folks, so supporting accessibility is the primary goal.