Those are interesting in limiting the short-term, but again I'm more about long-term attrition. With those, you might have trouble with a running fight because you won't be easily able to heal up to full, but a day of downtime and you'll be just like new. I like the idea of having to spend a week or two recovering. I feel like 5E encouraged my players go just break-neck around the place, even with "gritty" healing on.
In this case, I like having multiple options to heal. But I also want some limiting factor so that you don't just recover in a single day. Looking over the mechanic, Strain seems like a fantastic way of managing that: typically speaking a PF2 party isn't for lack of healing (especially with Fonts for Clerics), but I want them to have to manage that in some way. Having so much means that long-term healing isn't really something that happens... unless you put in a limit. Strain... that looks like it could do it.
The only situation I'd say that you might be able to heal from without Strain is from 0 hitpoints (which is fine, since the Wounded condition means you're not going to get much out of that edge case). In fact, you could probably do something about having levels of Wounded limiting how much strain you can recover until the condition is gone. Lot of potential in adding in that limit, just like Healing Surges were meant to do in 4E.