She might enjoy playing with the phonics bus
There isn’t any great advantage in learning letters early but a lot of dc can struggle with writing later if they’ve not done a lot of gross motor play as toddlers that promotes coordination and shoulder strength. Things like crawling through play tunnels, building tracks on the floor, finger painting or “helping” wash the windows with a sponge are all building towards writing skills. Playing with play dough or baking, washing and squeezing doll clothes and then hanging them on a line with pegs are creating fine motor strength.
In terms of maths skills, a set of cups for sand or water play (either at the sink or in the bath) or a box of dry rice, can teach them loads without you even saying a word. Just by holding and building towers with wooden blocks they are learning foundational skills that will help later with measurement and fractions. Helping to set the table for dinner covers a whole swathe of the Primary maths curriculum (number, categories, more/less than, what’s missing, set completion, etc)
A good primary teacher will teach letters and numbers in no time, but they can’t teach in a classroom what toddlers are learning through free play and from being with you.
You sound like a really caring mum and there are lots of blogs about early childhood education that might give you ideas for things to do with her.
To get back to letters and reading though, the phonics bus is fun. If you can find sand letters it adds another dimension to the letters. Magnetic ones that stick on the fridge are fun too. But one of the best things you can do is snuggle up and read to her so that she learns that reading is a pleasure and not a struggle (the same book over and over is also fine). Reading your own books too is great - mine used to come and tuck in beside me and sometimes pick out the letters they recognized, or rifle the pages and smell my books. All of that contributes a to an eventual love of reading.
Hope that helps. I’m sure you’re already doing lots of the above but sometimes we don’t see the educational value in the “ordinary” stuff.