On the business... depends if the family can pay the bills. Business is business, it's not a hobby.
Is this really a viable business, as your sole source of income year-round? Is it enough for the family, in addition to your DW's income? Or is it viable only alongside another income stream from you? Or is it a hobby that you make some money from (so a viable and attractive 'side hustle' but not truly a full-time business)?
Something I got from your post is that the way you contribute equally to bills, despite having very different incomes. That leaves your DW funding all the luxuries, so possibly having more control over them, while you're left with nothing for gifts etc. A more equitable approach is to contribute to bills and essentials proportionately to your income, then also having personal spending money left over. Or throwing everything into a big pot and budgeting form there, allowing each adult equal personal spending.
The approach you're taking is unfair on you, leaves you without spending money and makes you look mean, when actually you're just a lower earner but as part of a family that you presumably contribute to in other ways (pull your weight with housework etc) and as part of an overall approach that the two of you have agreed between you.
Have the two of you really agreed this between you though? Do you pull your weight in other ways?
The DCs' resentment of you, of needing to look after you, might convey that they are brats (who brought them up again?), or that you are resented more generally. Are you perceived as prioritising your enjoyment of a hobby-business above what is needed by your wife and family?
Also, the 'throw money at it' approach to gift-giving you conveyed at the top of the thread, the novelty of the idea of 'vouchers for time-based activities', could be taken to suggest a materialistic family generally, or that you are not used to doing the thinking about meeting your DCs' needs, that is that perhaps you don't pull your weight with housework and the mental load of family life.
I'd be interested to read your wife's pov, as I do wonder if she might portray herself as working full-time, being relied upon as the bread-winner and having to carry the mental load of family life, while you pootle about with a hobby-business and 'help' with a few practical tasks... Quite possibly not but I cannot help but put it out there.