Best way to use an iPhone for a blind person with impaired finger dexterity and slurred speech?

My elderly father who is essentially blind (blind in one eye and very low vision in other eye), recently got a stroke which caused him to lose his finger dexterity (he is unable to even swipe up to unlock the phone properly) and also caused his speech to be slurred (making voice control not ideal).

I am trying to figure something out for him so that he can regain autonomy to use his phone himself to do basic things like reading his messages, answering and making calls. The following are the Accessibility features I have tried so far with him over the last few weeks:

1) Siri Control

This works to a certain extent but because of his slurred speech it takes him many tries before Siri can understand him to make a call. Many times Siri ends up calling the wrong person. He is also unable to get Siri to do things outside of making calls as the specific phrases to get things done are not easy for him to remember and speaking loud, fast and clear enough for Siri to understand is not easy for him.

2) Voice Over

This does not work for him well at all. Even though this feature was made for the blind, the issue here is that it assumes the user has great finger dexterity and enough finger sensitivity to detect the vibrations of the phone. Many times because he cannot control his fingers properly, he ends up tapping or swiping the wrong item and it gets frustrating very quickly. Also, it is difficult for him to differentiate whether he is doing a finger swipe, tap or long press.

3) Voice Control

Using voice control alone is impossible for him as he is unable to see the screen. We could have some success if we use Voice Control together with Voice Over. Voice Over will read out the buttons and options on screen for him and he can control actions on the phone using his voice. But there are still some flaws to this method, eg. When turned on, Voice Over usually will read to you the next / previous item on screen if you swipe right or left on the phone, but if we ask Voice Control to do a "Swipe Right" or "Swipe Left", it does the swipe as though Voice Over is not turned on, (I also tried to do a custom gesture in Voice Control but it did not work as well) which then breaks the entire use of Voice Over. Even if we managed to solve this, him having to speak all the time to control his phone will be very tiring for him at his age as well.

4) Switch Control

This option seems the most promising for him, when Speech and Sound Effects are turned on, and Scanning Style set to Manual. We can use an external Bluetooth device such as a TV Remote for him to press the switches to go to the next or previous item and to do gestures like tapping. Pressing physical buttons is easier for him as he is able to feel where the buttons are with his hands without relying on his vision. But as always this solution is not perfect also, in switch control the way to do simple a "Scroll Down" action in an app for example WhatsApp takes 7 presses (Default Action > Next Item X2 > Tap> Scroll > Scroll Down > Tap) and to answer a call takes 6 button presses ( Next Item X5 > Tap).

So after evaluating all these options, it seems that the best solution is to custom build a Bluetooth remote to use with switch control which will have some special buttons that for example on one press, sends the command for the 6 button presses to the iPhone to pick up a call. But before diving into that I wanted to check on here to see if anyone has any insights on any other features, settings or combinations of features or even an App to download to use to achieve what we need.

Thanks in advance for anyone who replies!

P.S. If anyone from the iPhone Accessibility Team reads this, thank you so much for building in so many features for people with disabilities, it is really amazing how many features there are for every kind of disability one can think of. <3