Many, probably most, companies that make shower faucets make these. It's kind of hard to know what modern means these days, but your local big box store can surely order this one, for example:

https://www.deltafaucet.com/bathroom/product/51500

and they make others and so does everyone else. They're not hard to come by, just tricky to find on most manufacturer's websites.

Any grab bar requires proper blocking within the walls. Just "adding a bar" will not work as the bar does no good if it can be ripped from the wall. If this project is a gut-to-the-studs I suggest you seek a product from a plumbing supply store, not a Big Box.

We just bought an extra grab bar (in addition to the 2 being installed in the shower horizontally as grab bars) and mounted it vertically. Delta sells a bracket to hold the handheld shower head: it mounts to either of the 2 most common ADA grab bar diameters. You can also buy Speakman, Moen and Delta (IIRC) packages with the ADA slide bar, bracket and handheld/hose, but they didn't match the rest of my bars/faucets/etc. and were more expensive.

Kohler sells ADA grab bars that are narrower in diameter trim ends than most grab bars. (I feel that's what makes a grab bar look bad - the large diameter trim.) They are way more expensive that other brands' grab bars. I paid about $25 per bar from Harney Hardware - their diameter is nearly as small as Kohler's. HTH.

ETA This was a new bathroom - we had blocking put in for all bars during framing.

I would NOT recommend a grab bar handheld shower head combo. I specialize in accessible design and having it as a combo is in my opinion is not safe, because a grab bar is supposed to be at a position specific to your capabilities and limitations; so if you do needed it, it is a reactionary grasp, because falling only takes a split second. Also the combo grab bar will be at too high of a position, and not at a lower level since it needs to be lower as you fall down and not up.

I would recommend a separate slide bar typically placed on the inside corner of the shower, but can be placed anywhere that works for you. It can be placed lower, so if needed, can be reached at a sitting position, or for children to use.

I have purchased and used (for almost 9 years) the Kohler K-8524 (30") or the K-9069 (24") and they come in chrome, polished chrome and brushed nickel. I like these, because to move the shower head holder, you pinch the lever and slide it up or down. there is no knob or lever to turn and lock in place. It also stays in position, which is important.

As far as grab bars, as I mentioned, it needs to be installed specifically for your capabilities and limitations. But the most important thing is that it is secured in solid wood blocking. If anyone tells you that they will install it into a wood or metal stud, they do not know what they are doing.

A grab bar is supposed to hold 250 pounds of pull or push force. Unless you have large hands, I also recommend the 1-1/4-inch diameter and not the 1-1/2-inch that you typically see in accessible stalls.

There are thousands of grab bars, but it would depend on what you are looking for. There are Universal Design grab bars that don't look like the typical stainless steel ones. Also your budget will make a difference. But if you just want the grab bars for safety. then I would recommend ones made by Wingits. They have a knurled area that makes it non-slip. I have used them for almost 10 years. You can purchase them on Amazon now, which will make it easier to get.

Grab bars are not an add on in most instances they need to be planned ahead as mentioned.